{"id":2851,"date":"2026-06-12T03:31:17","date_gmt":"2026-06-12T03:31:17","guid":{"rendered":"https:\/\/industrialsafetysensor.com\/?p=2851"},"modified":"2026-09-12T09:07:27","modified_gmt":"2026-09-12T09:07:27","slug":"iso-13849-performance-level","status":"publish","type":"post","link":"https:\/\/industrialsafetysensor.com\/es\/blog\/iso-13849-performance-level\/","title":{"rendered":"Nivel de rendimiento ISO 13849 (PL ae) explicado para la seguridad de las m\u00e1quinas"},"content":{"rendered":"\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 01 \u2014 INTRODUCTION\r\n   Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-blog,\r\n.iso13849-blog *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-blog{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --muted:#687985;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  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background:var(--soft);\r\n}\r\n\r\n.iso13849-blog .reading-guide strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-blog .reading-guide p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-blog .inner{\r\n    padding:55px 20px 55px;\r\n  }\r\n\r\n  .iso13849-blog h1{\r\n    font-size:38px;\r\n  }\r\n\r\n  .iso13849-blog .deck{\r\n    font-size:18px;\r\n  }\r\n\r\n  .iso13849-blog .reference-row{\r\n    grid-template-columns:1fr;\r\n\r\n    gap:4px;\r\n  }\r\n\r\n  .iso13849-blog .reading-guide{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<article class=\"iso13849-blog\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"article-meta\">\r\n      Machine Safety \u00b7 Functional Safety\r\n    <\/div>\r\n\r\n    <h1>\r\n      ISO 13849 Performance Level (PL a\u2013e):\r\n      A Practical Guide to Machine Safety\r\n    <\/h1>\r\n\r\n    <p class=\"deck\">\r\n      A practical introduction to Performance Level, PLr, PFH,\r\n      Category, MTTF<sub>d<\/sub>, DC<sub>avg<\/sub>, CCF and the\r\n      engineering process used to evaluate safety-related control\r\n      functions under ISO 13849-1.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"intro-copy\">\r\n\r\n      <p>\r\n        When a machinery risk-reduction measure depends on a control system,\r\n        the safety-related parts of that control system need to perform their\r\n        intended safety function with an appropriate level of reliability.\r\n        ISO 13849-1 provides one of the principal methodologies used to\r\n        design and evaluate those safety-related control functions.\r\n      <\/p>\r\n\r\n      <p>\r\n        The standard uses five\r\n        <strong>Performance Levels \u2014 PL a, PL b, PL c, PL d and PL e<\/strong>.\r\n        Moving from PL a toward PL e represents progressively more demanding\r\n        safety-related performance and progressively lower permitted\r\n        frequencies of dangerous failure.\r\n      <\/p>\r\n\r\n      <p>\r\n        Performance Level is not determined by failure probability alone.\r\n        The evaluation also considers the architecture of the\r\n        safety-related control system, component reliability, diagnostic\r\n        capability, measures against common-cause failures and measures\r\n        intended to prevent systematic failures.\r\n      <\/p>\r\n\r\n      <p>\r\n        Another important distinction is between\r\n        <strong>PLr<\/strong> \u2014 the required Performance Level established\r\n        for a safety function \u2014 and the\r\n        <strong>achieved PL<\/strong> demonstrated by the implemented\r\n        safety-related control system.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <section class=\"quick-reference\">\r\n\r\n      <h2>\r\n        ISO 13849 at a glance\r\n      <\/h2>\r\n\r\n      <p class=\"quick-reference-intro\">\r\n        These concepts appear repeatedly throughout this guide.\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"reference-list\">\r\n\r\n        <li class=\"reference-row\">\r\n\r\n          <div class=\"reference-label\">\r\n            Current Part 1\r\n          <\/div>\r\n\r\n          <div class=\"reference-value\">\r\n            ISO 13849-1:2023, fourth edition.\r\n          <\/div>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"reference-row\">\r\n\r\n          <div class=\"reference-label\">\r\n            Performance scale\r\n          <\/div>\r\n\r\n          <div class=\"reference-value\">\r\n            PL a through PL e.\r\n          <\/div>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"reference-row\">\r\n\r\n          <div class=\"reference-label\">\r\n            PLr\r\n          <\/div>\r\n\r\n          <div class=\"reference-value\">\r\n            Required Performance Level for a defined safety function,\r\n            determined from risk assessment and applicable requirements.\r\n          <\/div>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"reference-row\">\r\n\r\n          <div class=\"reference-label\">\r\n            Achieved PL\r\n          <\/div>\r\n\r\n          <div class=\"reference-value\">\r\n            The Performance Level demonstrated by the designed and\r\n            evaluated safety-related control function.\r\n          <\/div>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"reference-row\">\r\n\r\n          <div class=\"reference-label\">\r\n            PFH\r\n          <\/div>\r\n\r\n          <div class=\"reference-value\">\r\n            Average frequency of a dangerous failure per hour.\r\n          <\/div>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"reference-row\">\r\n\r\n          <div class=\"reference-label\">\r\n            Main evaluation factors\r\n          <\/div>\r\n\r\n          <div class=\"reference-value\">\r\n            Category, MTTF<sub>d<\/sub>, DC<sub>avg<\/sub>, CCF,\r\n            systematic measures and the requirements applicable to\r\n            the complete safety function.\r\n          <\/div>\r\n\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n    <\/section>\r\n\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        Performance Level belongs to a safety function \u2014 not automatically\r\n        to the machine as a whole.\r\n      <\/strong>\r\n\r\n      <p>\r\n        ISO 13849-1 does not state that every machine of a particular type\r\n        must automatically be assigned PL c, PL d or PL e. The required PLr\r\n        depends on the defined safety function, the risk assessment and any\r\n        applicable machine-specific requirements.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <div class=\"reading-guide\">\r\n\r\n      <strong>\r\n        How to use this guide\r\n      <\/strong>\r\n\r\n      <p>\r\n        The article begins with the basic PL and PLr concepts, then moves\r\n        through risk assessment, architecture and reliability, PL versus SIL,\r\n        IEC 61496 ESPE Types, verification and validation, SISTEMA, and the\r\n        main changes introduced in ISO 13849-1:2023.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/article>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   TABLE OF CONTENTS\r\n   Place after Section 01\r\n========================================================= *\/\r\n\r\n.iso13849-toc,\r\n.iso13849-toc *{\r\n  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a:hover{\r\n  color:var(--blue-dark);\r\n}\r\n\r\n\r\n\/* MOBILE *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-toc .inner{\r\n    padding:\r\n      5px 20px\r\n      58px;\r\n  }\r\n\r\n  .iso13849-toc .toc-list{\r\n    grid-template-columns:1fr;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-toc\" aria-label=\"ISO 13849 article table of contents\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"toc-wrap\">\r\n\r\n      <span class=\"toc-label\">\r\n        On This Page\r\n      <\/span>\r\n\r\n      <h2>\r\n        Table of Contents\r\n      <\/h2>\r\n\r\n      <p class=\"toc-intro\">\r\n        Use the links below to jump directly to a topic in this guide.\r\n      <\/p>\r\n\r\n\r\n      <nav aria-label=\"Table of contents\">\r\n\r\n        <ol class=\"toc-list\">\r\n\r\n          <li>\r\n            <a href=\"#iso13849-introduction\">\r\n              Introduction &amp; Quick Guide\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#what-is-performance-level\">\r\n              What Is a Performance Level?\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#pl-pfh-bands\">\r\n              PL a\u2013e and PFH Bands\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#how-plr-is-determined\">\r\n              How Is PLr Determined?\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#achieved-performance-level\">\r\n              What Determines the Achieved PL?\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#worked-example\">\r\n              Generic Worked Example\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#performance-level-vs-sil\">\r\n              Performance Level vs SIL\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#espe-type-pl-sil\">\r\n              IEC 61496 Type 2, 3 &amp; 4\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#verification-validation-sistema\">\r\n              Verification, Validation &amp; SISTEMA\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#iso13849-2023-changes\">\r\n              What Changed in ISO 13849-1:2023?\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#common-misunderstandings\">\r\n              Common Misunderstandings\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#iso13849-faq\">\r\n              Frequently Asked Questions\r\n            <\/a>\r\n          <\/li>\r\n\r\n          <li>\r\n            <a href=\"#references-sources\">\r\n              References &amp; Sources\r\n            <\/a>\r\n          <\/li>\r\n\r\n        <\/ol>\r\n\r\n      <\/nav>\r\n\r\n    <\/div>\r\n\r\n  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*\/\r\n\r\n.iso13849-s02 .copy{\r\n  max-width:800px;\r\n  margin-top:35px;\r\n}\r\n\r\n.iso13849-s02 .copy p{\r\n  margin:0 0 22px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.9;\r\n}\r\n\r\n.iso13849-s02 strong{\r\n  color:var(--navy);\r\n}\r\n\r\n\r\n\/* ARTICLE PART *\/\r\n\r\n.iso13849-s02 .article-part{\r\n  max-width:800px;\r\n\r\n  margin-top:52px;\r\n  padding-top:40px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s02 .article-part h3{\r\n  margin:0 0 17px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:25px;\r\n  line-height:1.35;\r\n  font-weight:820;\r\n\r\n  letter-spacing:-.015em;\r\n}\r\n\r\n.iso13849-s02 .article-part p{\r\n  margin:0 0 20px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.88;\r\n}\r\n\r\n\r\n\/* FUNCTION CHAIN *\/\r\n\r\n.iso13849-s02 .function-list{\r\n  margin:25px 0 0;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n}\r\n\r\n.iso13849-s02 .function-list li{\r\n  position:relative;\r\n\r\n  padding:20px 0 20px 95px;\r\n\r\n  border-top:1px solid var(--line);\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n.iso13849-s02 .function-list li:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s02 .function-label{\r\n  position:absolute;\r\n\r\n  left:0;\r\n  top:20px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.06em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s02 .function-list strong{\r\n  display:block;\r\n\r\n  margin-bottom:5px;\r\n\r\n  font-size:15px;\r\n}\r\n\r\n\r\n\/* PLr vs PL *\/\r\n\r\n.iso13849-s02 .definition-pair{\r\n  margin-top:25px;\r\n}\r\n\r\n.iso13849-s02 .definition-row{\r\n  padding:22px 0;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s02 .definition-row:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s02 .definition-row h4{\r\n  margin:0 0 7px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:17px;\r\n  line-height:1.45;\r\n  font-weight:800;\r\n}\r\n\r\n.iso13849-s02 .definition-row p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* EQUATION *\/\r\n\r\n.iso13849-s02 .relationship{\r\n  margin-top:32px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:20px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n}\r\n\r\n\r\n\/* NOTE *\/\r\n\r\n.iso13849-s02 .editorial-note{\r\n  max-width:800px;\r\n\r\n  margin-top:40px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s02 .editorial-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  font-size:16px;\r\n}\r\n\r\n.iso13849-s02 .editorial-note p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* MOBILE *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s02 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s02 .function-list li{\r\n    padding-left:0;\r\n    padding-top:51px;\r\n  }\r\n\r\n  .iso13849-s02 .function-label{\r\n    top:18px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s02\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Understanding the Concept\r\n    <\/div>\r\n\r\n    <h2>\r\n      What Is a Performance Level?\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      A Performance Level describes the ability of a safety-related control\r\n      function to perform its intended safety action reliably under\r\n      foreseeable conditions.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        Identifying a machinery hazard is only the beginning of the\r\n        risk-reduction process. If a protective measure depends on a control\r\n        system, the relevant safety-related parts of that control system need\r\n        to provide sufficient performance for the required safety function.\r\n      <\/p>\r\n\r\n      <p>\r\n        ISO 13849-1 expresses this performance using five levels:\r\n        <strong>PL a, PL b, PL c, PL d and PL e<\/strong>.\r\n        The scale progresses toward increasingly demanding safety-related\r\n        performance and lower permitted frequencies of dangerous failure.\r\n      <\/p>\r\n\r\n      <p>\r\n        The final Performance Level is not simply a numerical reliability\r\n        value. It also reflects the architecture of the control system,\r\n        component reliability, diagnostic capability, resistance to\r\n        common-cause failures and measures against systematic failures.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Performance Level is evaluated for a safety function\r\n      <\/h3>\r\n\r\n      <p>\r\n        A safety function often involves several parts of the control system.\r\n        A useful conceptual model is to divide the function into input,\r\n        logic and output.\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"function-list\">\r\n\r\n        <li>\r\n\r\n          <span class=\"function-label\">\r\n            Input\r\n          <\/span>\r\n\r\n          <strong>\r\n            Detect the relevant condition\r\n          <\/strong>\r\n\r\n          The input portion provides safety-related information about a\r\n          condition that requires protective action.\r\n\r\n        <\/li>\r\n\r\n\r\n        <li>\r\n\r\n          <span class=\"function-label\">\r\n            Logic\r\n          <\/span>\r\n\r\n          <strong>\r\n            Evaluate the information\r\n          <\/strong>\r\n\r\n          The logic portion processes the safety-related input and determines\r\n          the required control response.\r\n\r\n        <\/li>\r\n\r\n\r\n        <li>\r\n\r\n          <span class=\"function-label\">\r\n            Output\r\n          <\/span>\r\n\r\n          <strong>\r\n            Achieve or maintain the safe state\r\n          <\/strong>\r\n\r\n          The output portion acts on the machine so that the required\r\n          protective action can be achieved.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        PLr and achieved PL describe different things\r\n      <\/h3>\r\n\r\n      <p>\r\n        One of the most useful distinctions in ISO 13849 is the difference\r\n        between the level that is required and the level that the completed\r\n        design actually achieves.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"definition-pair\">\r\n\r\n        <div class=\"definition-row\">\r\n\r\n          <h4>\r\n            PLr \u2014 Required Performance Level\r\n          <\/h4>\r\n\r\n          <p>\r\n            The Performance Level required for a defined safety function,\r\n            established from risk assessment and applicable machinery\r\n            requirements.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"definition-row\">\r\n\r\n          <h4>\r\n            Achieved PL\r\n          <\/h4>\r\n\r\n          <p>\r\n            The Performance Level demonstrated by the implemented\r\n            safety-related control function after architecture,\r\n            reliability, diagnostics and the other applicable requirements\r\n            have been evaluated.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/div>\r\n\r\n\r\n      <div class=\"relationship\">\r\n        Achieved PL \u2265 Required PLr\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        Higher is not automatically the design objective.\r\n      <\/strong>\r\n\r\n      <p>\r\n        The objective is to achieve sufficient performance for the required\r\n        risk reduction. PLr should come from the relevant risk assessment and\r\n        applicable standards rather than from an assumption that every safety\r\n        function should automatically be designed to PL e.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 03 \u2014 PL a\u2013e AND PFH\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s03,\r\n.iso13849-s03 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s03{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n\r\n  background:#f8fafb;\r\n\r\n  color:var(--text);\r\n\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s03 .inner{\r\n  max-width:880px;\r\n\r\n  margin:0 auto;\r\n\r\n  padding:76px 28px 82px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   HEADER\r\n========================================================= *\/\r\n\r\n.iso13849-s03 .eyebrow{\r\n  display:flex;\r\n  align-items:center;\r\n  gap:10px;\r\n\r\n  margin-bottom:15px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:12px;\r\n  line-height:1.4;\r\n  font-weight:800;\r\n\r\n  letter-spacing:.1em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s03 .eyebrow::before{\r\n  content:\"03\";\r\n\r\n  color:var(--blue);\r\n\r\n  font-size:12px;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s03 .eyebrow::after{\r\n  content:\"\";\r\n\r\n  width:34px;\r\n  height:1px;\r\n\r\n  background:#9fd8f3;\r\n}\r\n\r\n.iso13849-s03 h2{\r\n  max-width:820px;\r\n\r\n  margin:0;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:clamp(31px,4vw,43px);\r\n  line-height:1.16;\r\n  font-weight:850;\r\n\r\n  letter-spacing:-.025em;\r\n}\r\n\r\n.iso13849-s03 .lead{\r\n  max-width:800px;\r\n\r\n  margin:22px 0 0;\r\n\r\n  color:#465865;\r\n\r\n  font-size:18px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   BODY\r\n========================================================= *\/\r\n\r\n.iso13849-s03 .copy{\r\n  max-width:800px;\r\n\r\n  margin-top:35px;\r\n}\r\n\r\n.iso13849-s03 .copy p{\r\n  margin:0 0 22px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.9;\r\n}\r\n\r\n.iso13849-s03 strong{\r\n  color:var(--navy);\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TABLE\r\n========================================================= *\/\r\n\r\n.iso13849-s03 .table-section{\r\n  max-width:800px;\r\n\r\n  margin-top:47px;\r\n  padding-top:38px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s03 .table-section h3{\r\n  margin:0 0 12px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:24px;\r\n  line-height:1.35;\r\n  font-weight:820;\r\n\r\n  letter-spacing:-.015em;\r\n}\r\n\r\n.iso13849-s03 .table-intro{\r\n  margin:0 0 25px;\r\n\r\n  color:#5b6d78;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n.iso13849-s03 .table-wrap{\r\n  width:100%;\r\n\r\n  overflow-x:auto;\r\n\r\n  border-top:1px solid #cad5db;\r\n  border-bottom:1px solid #cad5db;\r\n}\r\n\r\n.iso13849-s03 table{\r\n  width:100%;\r\n\r\n  min-width:650px;\r\n\r\n  border-collapse:collapse;\r\n}\r\n\r\n.iso13849-s03 th{\r\n  padding:15px 17px;\r\n\r\n  border-bottom:2px solid #cad5db;\r\n\r\n  color:#536571;\r\n\r\n  text-align:left;\r\n\r\n  font-size:11px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.06em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s03 td{\r\n  padding:19px 17px;\r\n\r\n  border-bottom:1px solid #e4eaed;\r\n\r\n  color:#40535f;\r\n\r\n  font-size:14px;\r\n  line-height:1.7;\r\n\r\n  vertical-align:middle;\r\n}\r\n\r\n.iso13849-s03 tbody tr:last-child td{\r\n  border-bottom:0;\r\n}\r\n\r\n.iso13849-s03 .pl{\r\n  width:105px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:18px;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s03 .pfh{\r\n  font-family:\r\n    ui-monospace,\r\n    SFMono-Regular,\r\n    Menlo,\r\n    Monaco,\r\n    Consolas,\r\n    \"Liberation Mono\",\r\n    monospace;\r\n\r\n  color:#263b47;\r\n\r\n  font-size:13px;\r\n  font-weight:700;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   EXPLANATION\r\n========================================================= *\/\r\n\r\n.iso13849-s03 .article-part{\r\n  max-width:800px;\r\n\r\n  margin-top:49px;\r\n  padding-top:39px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s03 .article-part h3{\r\n  margin:0 0 17px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:25px;\r\n  line-height:1.35;\r\n  font-weight:820;\r\n\r\n  letter-spacing:-.015em;\r\n}\r\n\r\n.iso13849-s03 .article-part p{\r\n  margin:0 0 20px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.88;\r\n}\r\n\r\n.iso13849-s03 .article-part p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   EXAMPLE\r\n========================================================= *\/\r\n\r\n.iso13849-s03 .example{\r\n  max-width:800px;\r\n\r\n  margin-top:36px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s03 .example strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s03 .example p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   IMPORTANT NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s03 .editorial-note{\r\n  max-width:800px;\r\n\r\n  margin-top:43px;\r\n  padding:26px 29px;\r\n\r\n  background:#ffffff;\r\n}\r\n\r\n.iso13849-s03 .editorial-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s03 .editorial-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s03 .editorial-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TAKEAWAY\r\n========================================================= *\/\r\n\r\n.iso13849-s03 .takeaway{\r\n  max-width:800px;\r\n\r\n  margin-top:45px;\r\n  padding-top:28px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s03 .takeaway strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-s03 .takeaway p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s03 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s03 .editorial-note{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s03\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Performance Levels\r\n    <\/div>\r\n\r\n    <h2>\r\n      PL a to PL e and the PFH Ranges\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      ISO 13849-1 defines five Performance Levels using ranges of the\r\n      average frequency of a dangerous failure per hour, abbreviated PFH.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        Moving from PL a toward PL e represents progressively greater\r\n        safety-related performance. Quantitatively, the permitted average\r\n        frequency of dangerous failure becomes lower as the Performance\r\n        Level increases.\r\n      <\/p>\r\n\r\n      <p>\r\n        PFH is expressed in failures per hour and is therefore commonly\r\n        written using scientific notation. For example,\r\n        1 \u00d7 10<sup>\u22127<\/sup> per hour is one order of magnitude lower than\r\n        1 \u00d7 10<sup>\u22126<\/sup> per hour.\r\n      <\/p>\r\n\r\n      <p>\r\n        The PFH range is an important quantitative part of the Performance\r\n        Level concept, but it is not the only requirement that determines\r\n        whether a safety-related control function achieves a particular PL.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         CURRENT ISO 13849-1:2023 TABLE\r\n    ====================================================== -->\r\n\r\n    <div class=\"table-section\">\r\n\r\n      <h3>\r\n        Performance Level and PFH\r\n      <\/h3>\r\n\r\n      <p class=\"table-intro\">\r\n        ISO 13849-1:2023 defines the following PFH ranges for\r\n        Performance Levels a through e.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"table-wrap\">\r\n\r\n        <table>\r\n\r\n          <thead>\r\n\r\n            <tr>\r\n\r\n              <th>\r\n                Performance Level\r\n              <\/th>\r\n\r\n              <th>\r\n                Average Frequency of a Dangerous Failure per Hour\r\n              <\/th>\r\n\r\n            <\/tr>\r\n\r\n          <\/thead>\r\n\r\n\r\n          <tbody>\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL a\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                1 \u00d7 10<sup>\u22125<\/sup>\r\n                \u2264 PFH\r\n                &lt;\r\n                1 \u00d7 10<sup>\u22124<\/sup>\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL b\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                3 \u00d7 10<sup>\u22126<\/sup>\r\n                \u2264 PFH\r\n                &lt;\r\n                1 \u00d7 10<sup>\u22125<\/sup>\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL c\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                1 \u00d7 10<sup>\u22126<\/sup>\r\n                \u2264 PFH\r\n                &lt;\r\n                3 \u00d7 10<sup>\u22126<\/sup>\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL d\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                1 \u00d7 10<sup>\u22127<\/sup>\r\n                \u2264 PFH\r\n                &lt;\r\n                1 \u00d7 10<sup>\u22126<\/sup>\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL e\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                PFH\r\n                &lt;\r\n                1 \u00d7 10<sup>\u22127<\/sup>\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n          <\/tbody>\r\n\r\n        <\/table>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         WHAT PFH MEANS\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        What does a lower PFH mean?\r\n      <\/h3>\r\n\r\n      <p>\r\n        A lower PFH represents a lower average frequency of dangerous\r\n        failure attributable to the safety-related control function.\r\n        It is therefore one quantitative measure of the dependability\r\n        required from that function.\r\n      <\/p>\r\n\r\n      <p>\r\n        PFH should not, however, be interpreted as a prediction of when\r\n        an accident will occur. It is a probabilistic functional-safety\r\n        measure used in the evaluation of the safety-related control\r\n        system.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"example\">\r\n\r\n      <strong>\r\n        Example of reading the scale\r\n      <\/strong>\r\n\r\n      <p>\r\n        PL d covers PFH values from 1 \u00d7 10<sup>\u22127<\/sup> per hour up to,\r\n        but not including, 1 \u00d7 10<sup>\u22126<\/sup> per hour. A design cannot\r\n        be classified as PL d merely because one component falls within\r\n        that range; the complete ISO 13849 requirements still apply.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         NOT PFH ALONE\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Why PFH alone does not establish the Performance Level\r\n      <\/h3>\r\n\r\n      <p>\r\n        ISO 13849 combines quantitative reliability with architectural and\r\n        qualitative requirements. The resulting Performance Level therefore\r\n        depends on more than the calculated dangerous-failure frequency.\r\n      <\/p>\r\n\r\n      <p>\r\n        The evaluation also considers factors such as Category,\r\n        MTTF<sub>d<\/sub>, DC<sub>avg<\/sub>, common-cause-failure measures\r\n        and requirements intended to prevent systematic failures.\r\n      <\/p>\r\n\r\n      <p>\r\n        These factors are discussed in more detail later in this guide.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        PFH is not the same as product lifetime or accident frequency.\r\n      <\/strong>\r\n\r\n      <p>\r\n        A PFH value should not be converted into statements such as\r\n        \u201cthis machine will run for a certain number of years before a\r\n        dangerous event occurs.\u201d\r\n      <\/p>\r\n\r\n      <p>\r\n        Functional-safety probability values describe the statistical\r\n        performance of the safety-related control function within the\r\n        applicable evaluation methodology. They do not predict the date\r\n        of a future accident or define the mechanical service life of\r\n        the equipment.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <div class=\"takeaway\">\r\n\r\n      <strong>\r\n        Key takeaway\r\n      <\/strong>\r\n\r\n      <p>\r\n        PFH provides the quantitative backbone of the PL scale, but an\r\n        achieved Performance Level is demonstrated through the complete\r\n        ISO 13849 design and evaluation process \u2014 not from PFH alone.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 04 \u2014 PLr DETERMINATION\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s04-blog,\r\n.iso13849-s04-blog *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s04-blog{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  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.article-part p{\r\n  margin:0 0 20px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.88;\r\n}\r\n\r\n.iso13849-s04-blog .article-part p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* TYPE-C NOTE *\/\r\n\r\n.iso13849-s04-blog .typec-note{\r\n  max-width:800px;\r\n\r\n  margin-top:39px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s04-blog .typec-note .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.1em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s04-blog .typec-note p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* RISK DEFINITIONS *\/\r\n\r\n.iso13849-s04-blog .risk-definitions{\r\n  max-width:800px;\r\n  margin-top:28px;\r\n}\r\n\r\n.iso13849-s04-blog .risk-item{\r\n  display:grid;\r\n\r\n  grid-template-columns:54px minmax(0,1fr);\r\n\r\n  gap:20px;\r\n\r\n  padding:24px 0;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s04-blog .risk-item:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s04-blog .risk-symbol{\r\n  color:var(--blue-dark);\r\n\r\n  font-size:27px;\r\n  line-height:1.2;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s04-blog .risk-content h4{\r\n  margin:1px 0 7px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:18px;\r\n  line-height:1.4;\r\n  font-weight:800;\r\n}\r\n\r\n.iso13849-s04-blog .risk-content p{\r\n  margin:0 0 9px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.78;\r\n}\r\n\r\n.iso13849-s04-blog .risk-content p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* PROCESS *\/\r\n\r\n.iso13849-s04-blog .process{\r\n  max-width:800px;\r\n\r\n  margin-top:27px;\r\n\r\n  counter-reset:plrstep;\r\n}\r\n\r\n.iso13849-s04-blog .process-step{\r\n  position:relative;\r\n\r\n  margin-left:19px;\r\n  padding:0 0 30px 35px;\r\n\r\n  border-left:1px solid #cfd9df;\r\n\r\n  counter-increment:plrstep;\r\n}\r\n\r\n.iso13849-s04-blog .process-step:last-child{\r\n  padding-bottom:0;\r\n  border-left-color:transparent;\r\n}\r\n\r\n.iso13849-s04-blog .process-step::before{\r\n  content:counter(plrstep);\r\n\r\n  position:absolute;\r\n\r\n  left:-19px;\r\n  top:-2px;\r\n\r\n  display:flex;\r\n  align-items:center;\r\n  justify-content:center;\r\n\r\n  width:37px;\r\n  height:37px;\r\n\r\n  background:#ffffff;\r\n\r\n  border:1px solid #9bcfe8;\r\n  border-radius:50%;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:12px;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s04-blog .process-step h4{\r\n  margin:0 0 6px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:17px;\r\n  line-height:1.45;\r\n  font-weight:800;\r\n}\r\n\r\n.iso13849-s04-blog .process-step p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.78;\r\n}\r\n\r\n\r\n\/* P PARAMETER LIST *\/\r\n\r\n.iso13849-s04-blog .plain-list{\r\n  margin:18px 0 4px;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n}\r\n\r\n.iso13849-s04-blog .plain-list li{\r\n  position:relative;\r\n\r\n  margin:11px 0;\r\n  padding-left:20px;\r\n\r\n  color:#455864;\r\n\r\n  font-size:14px;\r\n  line-height:1.76;\r\n}\r\n\r\n.iso13849-s04-blog .plain-list li::before{\r\n  content:\"\";\r\n\r\n  position:absolute;\r\n\r\n  left:2px;\r\n  top:.73em;\r\n\r\n  width:5px;\r\n  height:5px;\r\n\r\n  background:var(--blue);\r\n\r\n  border-radius:50%;\r\n}\r\n\r\n\r\n\/* 2023 NOTE *\/\r\n\r\n.iso13849-s04-blog .p-note{\r\n  max-width:800px;\r\n\r\n  margin-top:35px;\r\n  padding:26px 29px;\r\n\r\n  background:var(--soft);\r\n}\r\n\r\n.iso13849-s04-blog .p-note .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s04-blog .p-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s04-blog .p-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s04-blog .p-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* EDITORIAL NOTE *\/\r\n\r\n.iso13849-s04-blog .editorial-note{\r\n  max-width:800px;\r\n\r\n  margin-top:42px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s04-blog .editorial-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s04-blog .editorial-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s04-blog .editorial-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* TAKEAWAY *\/\r\n\r\n.iso13849-s04-blog .takeaway{\r\n  max-width:800px;\r\n\r\n  margin-top:46px;\r\n  padding-top:28px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s04-blog .takeaway strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-s04-blog .takeaway p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* MOBILE *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s04-blog .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s04-blog .risk-item{\r\n    grid-template-columns:42px minmax(0,1fr);\r\n\r\n    gap:14px;\r\n  }\r\n\r\n  .iso13849-s04-blog .risk-symbol{\r\n    font-size:23px;\r\n  }\r\n\r\n  .iso13849-s04-blog .p-note{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s04-blog\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Required Performance Level\r\n    <\/div>\r\n\r\n    <h2>\r\n      How Is the Required Performance Level (PLr) Determined?\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      PLr is established for a defined safety function. It represents the\r\n      level of safety-related control performance required to contribute\r\n      the necessary risk reduction.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        The process begins with the machinery risk assessment and the\r\n        definition of the safety function \u2014 not with the selection of a\r\n        particular safety device or control architecture.\r\n      <\/p>\r\n\r\n      <p>\r\n        The important question is therefore not simply\r\n        <strong>\u201cWhat PL does this machine need?\u201d<\/strong> but:\r\n        what safety function is required for the identified hazard, and\r\n        what level of performance must that function achieve?\r\n      <\/p>\r\n\r\n      <p>\r\n        A machine can contain several hazards, operating modes and safety\r\n        functions. Those functions do not necessarily have the same PLr,\r\n        so the required Performance Level should be considered\r\n        function by function.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <aside class=\"typec-note\">\r\n\r\n      <span class=\"label\">\r\n        Machine-specific requirements matter\r\n      <\/span>\r\n\r\n      <p>\r\n        Before relying only on a generic risk-graph assessment, check\r\n        whether an applicable Type-C machine safety standard defines\r\n        particular safety functions, protective measures or required\r\n        safety performance for the machine concerned.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- S F P -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        The S\u2013F\u2013P risk parameters\r\n      <\/h3>\r\n\r\n      <p>\r\n        The ISO 13849 risk graph considers three principal parameters:\r\n        severity of possible injury, frequency and\/or duration of exposure\r\n        to the hazard, and the possibility of avoiding the hazard or\r\n        limiting the harm.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"risk-definitions\">\r\n\r\n        <div class=\"risk-item\">\r\n\r\n          <div class=\"risk-symbol\">\r\n            S\r\n          <\/div>\r\n\r\n          <div class=\"risk-content\">\r\n\r\n            <h4>\r\n              Severity of injury\r\n            <\/h4>\r\n\r\n            <p>\r\n              Consider the reasonably foreseeable consequence if the\r\n              hazardous event occurs.\r\n            <\/p>\r\n\r\n            <p>\r\n              <strong>S1<\/strong> \u2014 slight, normally reversible injury.\r\n            <\/p>\r\n\r\n            <p>\r\n              <strong>S2<\/strong> \u2014 serious, normally irreversible injury,\r\n              including death.\r\n            <\/p>\r\n\r\n          <\/div>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"risk-item\">\r\n\r\n          <div class=\"risk-symbol\">\r\n            F\r\n          <\/div>\r\n\r\n          <div class=\"risk-content\">\r\n\r\n            <h4>\r\n              Frequency and\/or exposure to the hazard\r\n            <\/h4>\r\n\r\n            <p>\r\n              Consider how often a person is exposed to the hazardous\r\n              situation and how long the exposure lasts.\r\n            <\/p>\r\n\r\n            <p>\r\n              <strong>F1<\/strong> \u2014 seldom to less frequent and\/or\r\n              exposure time is short.\r\n            <\/p>\r\n\r\n            <p>\r\n              <strong>F2<\/strong> \u2014 frequent to continuous and\/or\r\n              exposure time is long.\r\n            <\/p>\r\n\r\n          <\/div>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"risk-item\">\r\n\r\n          <div class=\"risk-symbol\">\r\n            P\r\n          <\/div>\r\n\r\n          <div class=\"risk-content\">\r\n\r\n            <h4>\r\n              Possibility of avoiding the hazard or limiting harm\r\n            <\/h4>\r\n\r\n            <p>\r\n              Consider whether a person could realistically avoid the\r\n              hazardous event or limit the resulting harm.\r\n            <\/p>\r\n\r\n            <p>\r\n              <strong>P1<\/strong> \u2014 possible under specific conditions.\r\n            <\/p>\r\n\r\n            <p>\r\n              <strong>P2<\/strong> \u2014 scarcely possible.\r\n            <\/p>\r\n\r\n          <\/div>\r\n\r\n        <\/div>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- PROCESS -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        PLr determination sits inside a wider risk-reduction process\r\n      <\/h3>\r\n\r\n      <p>\r\n        The risk graph is a structured method for determining the required\r\n        Performance Level of a safety function. It should not be treated as\r\n        a substitute for the complete machinery risk assessment.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"process\">\r\n\r\n        <div class=\"process-step\">\r\n\r\n          <h4>\r\n            Identify the hazard and hazardous situation\r\n          <\/h4>\r\n\r\n          <p>\r\n            Determine what can cause harm, who may be exposed and the\r\n            reasonably foreseeable consequences.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"process-step\">\r\n\r\n          <h4>\r\n            Define the required safety function\r\n          <\/h4>\r\n\r\n          <p>\r\n            Describe what the safety-related control system must do to\r\n            contribute the required risk reduction.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"process-step\">\r\n\r\n          <h4>\r\n            Determine PLr\r\n          <\/h4>\r\n\r\n          <p>\r\n            Consider applicable machine-specific requirements and apply the\r\n            appropriate risk-evaluation method to the defined safety\r\n            function.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"process-step\">\r\n\r\n          <h4>\r\n            Design and evaluate the safety-related control system\r\n          <\/h4>\r\n\r\n          <p>\r\n            The implemented function is then designed, evaluated, verified\r\n            and validated to demonstrate that its achieved PL is sufficient\r\n            for the required PLr.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- PARAMETER P -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Parameter P requires more than asking whether someone can \u201cstep away\u201d\r\n      <\/h3>\r\n\r\n      <p>\r\n        The possibility of avoiding the hazard or limiting harm can be one\r\n        of the more difficult risk-graph judgements. ISO 13849-1:2023\r\n        provides more structured guidance for this assessment.\r\n      <\/p>\r\n\r\n      <p>\r\n        The evaluation can consider five practical factors:\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          whether the machine is operated by a specialist or by a\r\n          non-specialist \/ layperson;\r\n        <\/li>\r\n\r\n        <li>\r\n          the speed of the machine part or process capable of producing\r\n          the hazardous event;\r\n        <\/li>\r\n\r\n        <li>\r\n          the physical possibility of avoiding the hazard;\r\n        <\/li>\r\n\r\n        <li>\r\n          the possibility of recognising or sensing the hazard in time; and\r\n        <\/li>\r\n\r\n        <li>\r\n          the complexity of the operation or interaction.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"p-note\">\r\n\r\n      <span class=\"label\">\r\n        ISO 13849-1:2023\r\n      <\/span>\r\n\r\n      <strong>\r\n        Parameter P should reflect realistic conditions, not an optimistic\r\n        assumption.\r\n      <\/strong>\r\n\r\n      <p>\r\n        The assessment should consider how the person actually interacts\r\n        with the machine and whether avoidance remains credible under the\r\n        foreseeable conditions of the hazardous situation.\r\n      <\/p>\r\n\r\n      <p>\r\n        The five-factor guidance helps make the P1\/P2 judgement more\r\n        structured than a simple yes-or-no question.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- ENGINEERING ORDER -->\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        Do not work backwards from a preferred safety solution.\r\n      <\/strong>\r\n\r\n      <p>\r\n        PLr should follow from the hazard, the defined safety function and\r\n        the required risk reduction. Selecting a preferred device,\r\n        architecture or Performance Level first and then adjusting the risk\r\n        assessment to justify it reverses the intended engineering process.\r\n      <\/p>\r\n\r\n      <p>\r\n        The same machine can also contain several safety functions with\r\n        different PLr values.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <div class=\"takeaway\">\r\n\r\n      <strong>\r\n        Key takeaway\r\n      <\/strong>\r\n\r\n      <p>\r\n        Determine PLr for a defined safety function within the complete\r\n        machinery risk-assessment process. Consider applicable\r\n        machine-specific requirements and use the S\u2013F\u2013P risk graph as a\r\n        structured decision aid rather than as a stand-alone safety\r\n        calculator.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 05 \u2014 WHAT DETERMINES THE ACHIEVED PL?\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s05,\r\n.iso13849-s05 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s05{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n  background:#f8fafb;\r\n\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s05 .inner{\r\n  max-width:880px;\r\n  margin:0 auto;\r\n  padding:78px 28px 84px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   HEADER\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .eyebrow{\r\n  display:flex;\r\n  align-items:center;\r\n  gap:10px;\r\n\r\n  margin-bottom:15px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:12px;\r\n  line-height:1.4;\r\n  font-weight:800;\r\n\r\n  letter-spacing:.1em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s05 .eyebrow::before{\r\n  content:\"05\";\r\n\r\n  color:var(--blue);\r\n\r\n  font-size:12px;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s05 .eyebrow::after{\r\n  content:\"\";\r\n\r\n  width:34px;\r\n  height:1px;\r\n\r\n  background:#9fd8f3;\r\n}\r\n\r\n.iso13849-s05 h2{\r\n  max-width:820px;\r\n\r\n  margin:0;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:clamp(31px,4vw,43px);\r\n  line-height:1.16;\r\n  font-weight:850;\r\n\r\n  letter-spacing:-.025em;\r\n}\r\n\r\n.iso13849-s05 .lead{\r\n  max-width:800px;\r\n\r\n  margin:22px 0 0;\r\n\r\n  color:#465865;\r\n\r\n  font-size:18px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   BODY\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .copy{\r\n  max-width:800px;\r\n  margin-top:35px;\r\n}\r\n\r\n.iso13849-s05 .copy p{\r\n  margin:0 0 22px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.9;\r\n}\r\n\r\n.iso13849-s05 strong{\r\n  color:var(--navy);\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   ARTICLE PART\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .article-part{\r\n  max-width:800px;\r\n\r\n  margin-top:52px;\r\n  padding-top:40px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s05 .article-part h3{\r\n  margin:0 0 17px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:25px;\r\n  line-height:1.35;\r\n  font-weight:820;\r\n\r\n  letter-spacing:-.015em;\r\n}\r\n\r\n.iso13849-s05 .article-part p{\r\n  margin:0 0 20px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.88;\r\n}\r\n\r\n.iso13849-s05 .article-part p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   CATEGORY LIST\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .category-list{\r\n  max-width:800px;\r\n\r\n  margin:27px 0 0;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n}\r\n\r\n.iso13849-s05 .category-item{\r\n  position:relative;\r\n\r\n  padding:24px 0 24px 94px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s05 .category-item:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s05 .category-name{\r\n  position:absolute;\r\n\r\n  left:0;\r\n  top:24px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:13px;\r\n  line-height:1.5;\r\n  font-weight:900;\r\n\r\n  letter-spacing:.03em;\r\n}\r\n\r\n.iso13849-s05 .category-item strong{\r\n  display:block;\r\n\r\n  margin-bottom:6px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s05 .category-item p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   PLAIN LIST\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .plain-list{\r\n  margin:18px 0 4px;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n}\r\n\r\n.iso13849-s05 .plain-list li{\r\n  position:relative;\r\n\r\n  margin:10px 0;\r\n  padding-left:20px;\r\n\r\n  color:#455864;\r\n\r\n  font-size:14px;\r\n  line-height:1.76;\r\n}\r\n\r\n.iso13849-s05 .plain-list li::before{\r\n  content:\"\";\r\n\r\n  position:absolute;\r\n\r\n  left:2px;\r\n  top:.73em;\r\n\r\n  width:5px;\r\n  height:5px;\r\n\r\n  background:var(--blue);\r\n\r\n  border-radius:50%;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   DEFINITION NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .definition-note{\r\n  max-width:800px;\r\n\r\n  margin-top:33px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s05 .definition-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s05 .definition-note p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   CATEGORY 3 \/ 4 DISTINCTION\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .cat34-note{\r\n  max-width:800px;\r\n\r\n  margin-top:38px;\r\n  padding:26px 29px;\r\n\r\n  background:#ffffff;\r\n}\r\n\r\n.iso13849-s05 .cat34-note .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s05 .cat34-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s05 .cat34-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s05 .cat34-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   SUMMARY\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .summary{\r\n  max-width:800px;\r\n\r\n  margin-top:49px;\r\n  padding-top:31px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s05 .summary-label{\r\n  display:block;\r\n\r\n  margin-bottom:12px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.1em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s05 .summary-line{\r\n  margin:0;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:20px;\r\n  line-height:1.65;\r\n  font-weight:820;\r\n}\r\n\r\n.iso13849-s05 .summary-caption{\r\n  margin:14px 0 0;\r\n\r\n  color:#647580;\r\n\r\n  font-size:13px;\r\n  line-height:1.78;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TAKEAWAY\r\n========================================================= *\/\r\n\r\n.iso13849-s05 .takeaway{\r\n  max-width:800px;\r\n\r\n  margin-top:42px;\r\n  padding-top:28px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s05 .takeaway strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-s05 .takeaway p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s05 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s05 .category-item{\r\n    padding-left:0;\r\n    padding-top:54px;\r\n  }\r\n\r\n  .iso13849-s05 .category-name{\r\n    top:22px;\r\n  }\r\n\r\n  .iso13849-s05 .cat34-note{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s05\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Achieved Performance Level\r\n    <\/div>\r\n\r\n    <h2>\r\n      What Determines the Achieved Performance Level?\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      The achieved PL depends on the complete safety-related control\r\n      function. No single Category, component rating or reliability\r\n      figure is sufficient on its own.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        After PLr has been determined, the safety-related control system\r\n        must be designed and evaluated to establish the Performance Level\r\n        it actually achieves.\r\n      <\/p>\r\n\r\n      <p>\r\n        For self-developed subsystems, several ISO 13849 parameters are\r\n        particularly important:\r\n        <strong>Category<\/strong>,\r\n        <strong>MTTF<sub>d<\/sub><\/strong>,\r\n        <strong>DC<sub>avg<\/sub><\/strong> and\r\n        <strong>CCF<\/strong>.\r\n      <\/p>\r\n\r\n      <p>\r\n        Requirements relating to systematic failures, software, component\r\n        selection, environmental influences and correct implementation also\r\n        form part of the safety argument.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         CATEGORY\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Category describes architecture and fault behaviour\r\n      <\/h3>\r\n\r\n      <p>\r\n        ISO 13849 uses Categories B, 1, 2, 3 and 4 as designated\r\n        architectures. They describe structural principles and how the\r\n        safety-related control subsystem is expected to behave when faults\r\n        occur.\r\n      <\/p>\r\n\r\n      <p>\r\n        Moving from Category B toward Category 4 generally introduces more\r\n        demanding requirements relating to component reliability, testing,\r\n        fault tolerance and fault detection.\r\n      <\/p>\r\n\r\n      <p>\r\n        But the Category number is <strong>not itself the achieved PL<\/strong>.\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"category-list\">\r\n\r\n\r\n        <li class=\"category-item\">\r\n\r\n          <span class=\"category-name\">\r\n            Cat. B\r\n          <\/span>\r\n\r\n          <strong>\r\n            Basic safety principles\r\n          <\/strong>\r\n\r\n          <p>\r\n            The safety-related parts are designed, constructed, selected,\r\n            assembled and combined in accordance with the relevant standards\r\n            so that they can withstand the expected influences, using basic\r\n            safety principles.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"category-item\">\r\n\r\n          <span class=\"category-name\">\r\n            Cat. 1\r\n          <\/span>\r\n\r\n          <strong>\r\n            Well-tried principles and increased component reliability\r\n          <\/strong>\r\n\r\n          <p>\r\n            Category 1 builds on Category B and uses well-tried safety\r\n            principles together with well-tried components where required.\r\n            The architecture remains fundamentally single-channel, so\r\n            resistance to dangerous failure relies heavily on component\r\n            reliability.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"category-item\">\r\n\r\n          <span class=\"category-name\">\r\n            Cat. 2\r\n          <\/span>\r\n\r\n          <strong>\r\n            Safety function with periodic or demand-related testing\r\n          <\/strong>\r\n\r\n          <p>\r\n            Category 2 introduces a test function that checks the safety\r\n            function at defined intervals or under defined conditions.\r\n            A dangerous fault can exist between tests, so the effectiveness\r\n            and timing of testing are important parts of the architecture.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"category-item\">\r\n\r\n          <span class=\"category-name\">\r\n            Cat. 3\r\n          <\/span>\r\n\r\n          <strong>\r\n            Single-fault tolerance with partial fault detection\r\n          <\/strong>\r\n\r\n          <p>\r\n            A single fault must not cause loss of the safety function.\r\n            Single faults should be detected at or before the next demand\r\n            whenever reasonably practicable. Because not every dangerous\r\n            fault necessarily has to be detected, an accumulation of\r\n            undetected faults can still lead to loss of the safety function.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"category-item\">\r\n\r\n          <span class=\"category-name\">\r\n            Cat. 4\r\n          <\/span>\r\n\r\n          <strong>\r\n            Single-fault tolerance with more demanding fault behaviour\r\n          <\/strong>\r\n\r\n          <p>\r\n            A single fault must not cause loss of the safety function and\r\n            should be detected at or before the next demand. Where detection\r\n            is not possible, the accumulation of undetected faults must not\r\n            result in loss of the safety function.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n      <\/ul>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"cat34-note\">\r\n\r\n      <span class=\"label\">\r\n        Category 3 vs Category 4\r\n      <\/span>\r\n\r\n      <strong>\r\n        The key distinction is not simply \u201ctwo channels versus two channels.\u201d\r\n      <\/strong>\r\n\r\n      <p>\r\n        Both Categories are commonly implemented with redundant structures,\r\n        but redundancy alone does not define the Category.\r\n      <\/p>\r\n\r\n      <p>\r\n        Category 3 permits situations in which some dangerous faults remain\r\n        undetected and their accumulation can eventually cause loss of the\r\n        safety function. Category 4 places a stronger requirement on fault\r\n        detection and fault accumulation so that the required safety\r\n        function is preserved under the defined fault conditions.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         MTTFd\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        MTTF<sub>d<\/sub>: resistance to dangerous random failure\r\n      <\/h3>\r\n\r\n      <p>\r\n        MTTF<sub>d<\/sub> means\r\n        <strong>Mean Time To Dangerous Failure<\/strong>. It is a statistical\r\n        reliability parameter used in ISO 13849 to characterise the\r\n        resistance of a channel or relevant component arrangement to\r\n        dangerous failure.\r\n      <\/p>\r\n\r\n      <p>\r\n        It should not be interpreted as guaranteed physical product life.\r\n        An MTTF<sub>d<\/sub> value is an input to the functional-safety\r\n        calculation rather than a promise that a component will operate for\r\n        that number of years before failing.\r\n      <\/p>\r\n\r\n      <p>\r\n        Two subsystems with similar architectures can therefore produce\r\n        different achieved Performance Levels if the reliability of their\r\n        components or channels differs significantly.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         DCavg\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        DC<sub>avg<\/sub>: effectiveness of dangerous-fault detection\r\n      <\/h3>\r\n\r\n      <p>\r\n        Diagnostic Coverage describes the extent to which diagnostics detect\r\n        dangerous failures. ISO 13849 uses\r\n        <strong>DC<sub>avg<\/sub><\/strong> to represent the average diagnostic\r\n        coverage for the relevant parts of the subsystem.\r\n      <\/p>\r\n\r\n      <p>\r\n        Diagnostics can include cross-monitoring, plausibility checks,\r\n        output monitoring, test pulses or other measures depending on the\r\n        technology and architecture.\r\n      <\/p>\r\n\r\n      <p>\r\n        Higher diagnostic coverage can improve the safety performance of a\r\n        suitable architecture, but DC<sub>avg<\/sub> cannot establish a PL\r\n        independently of Category, reliability and the other applicable\r\n        requirements.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         CCF\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        CCF: keeping redundancy from failing for the same reason\r\n      <\/h3>\r\n\r\n      <p>\r\n        Redundant channels provide little benefit if one shared cause can\r\n        defeat them at the same time. ISO 13849 therefore requires\r\n        consideration of <strong>Common Cause Failure (CCF)<\/strong> where\r\n        relevant.\r\n      <\/p>\r\n\r\n      <p>\r\n        Measures against CCF can address matters such as:\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          physical or functional separation;\r\n        <\/li>\r\n\r\n        <li>\r\n          protection against environmental influences;\r\n        <\/li>\r\n\r\n        <li>\r\n          electrical, mechanical and electromagnetic independence;\r\n        <\/li>\r\n\r\n        <li>\r\n          suitable component or technology diversity where appropriate;\r\n        <\/li>\r\n\r\n        <li>\r\n          systematic analysis of potential shared failure causes; and\r\n        <\/li>\r\n\r\n        <li>\r\n          competence and engineering practices appropriate to the design.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n      <p>\r\n        ISO 13849-1:2023 places clearer emphasis on considering CCF at\r\n        subsystem level rather than assuming that one generic CCF assessment\r\n        automatically covers every part of a complex safety function.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         SYSTEMATIC FAILURES\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Random hardware failure is only part of the picture\r\n      <\/h3>\r\n\r\n      <p>\r\n        A safety function can fail even when the probabilistic hardware\r\n        calculation looks satisfactory.\r\n      <\/p>\r\n\r\n      <p>\r\n        Specification mistakes, unsuitable component application, software\r\n        errors, incorrect parameterisation, wiring errors, integration\r\n        mistakes or uncontrolled modifications can introduce\r\n        <strong>systematic failures<\/strong>.\r\n      <\/p>\r\n\r\n      <p>\r\n        ISO 13849 therefore includes requirements and guidance intended to\r\n        prevent or control these failures throughout specification, design,\r\n        implementation, verification and validation.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         IMPORTANT DISTINCTION\r\n    ====================================================== -->\r\n\r\n    <aside class=\"definition-note\">\r\n\r\n      <strong>\r\n        Category 3 does not automatically mean PL d, and Category 4 does\r\n        not automatically mean PL e.\r\n      <\/strong>\r\n\r\n      <p>\r\n        Category defines an architectural framework. The achieved\r\n        Performance Level depends on the combination of architecture,\r\n        MTTF<sub>d<\/sub>, DC<sub>avg<\/sub>, CCF and the fulfilment of the\r\n        other applicable ISO 13849 requirements.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         SUMMARY\r\n    ====================================================== -->\r\n\r\n    <div class=\"summary\">\r\n\r\n      <span class=\"summary-label\">\r\n        Conceptual relationship\r\n      <\/span>\r\n\r\n      <p class=\"summary-line\">\r\n        Architecture + component reliability + diagnostics +\r\n        fault independence + systematic integrity\r\n        \u2192 achieved safety performance\r\n      <\/p>\r\n\r\n      <p class=\"summary-caption\">\r\n        This is a conceptual summary, not the ISO 13849 calculation\r\n        formula. The actual Performance Level must be established using\r\n        the methodology and requirements of the standard.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         TAKEAWAY\r\n    ====================================================== -->\r\n\r\n    <div class=\"takeaway\">\r\n\r\n      <strong>\r\n        Key takeaway\r\n      <\/strong>\r\n\r\n      <p>\r\n        The achieved PL belongs to the implemented safety function or\r\n        subsystem as evaluated. It cannot be inferred from the Category\r\n        number, the presence of redundancy, or the rating of one individual\r\n        safety component.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 06 \u2014 GENERIC WORKED EXAMPLE\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s06,\r\n.iso13849-s06 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s06{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s06 .inner{\r\n  max-width:880px;\r\n\r\n  margin:0 auto;\r\n\r\n  padding:78px 28px 84px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   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line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   BODY\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .copy{\r\n  max-width:800px;\r\n\r\n  margin-top:35px;\r\n}\r\n\r\n.iso13849-s06 .copy p{\r\n  margin:0 0 22px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.9;\r\n}\r\n\r\n.iso13849-s06 strong{\r\n  color:var(--navy);\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   ARTICLE PART\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .article-part{\r\n  max-width:800px;\r\n\r\n  margin-top:52px;\r\n  padding-top:40px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s06 .article-part h3{\r\n  margin:0 0 17px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:25px;\r\n  line-height:1.35;\r\n  font-weight:820;\r\n\r\n  letter-spacing:-.015em;\r\n}\r\n\r\n.iso13849-s06 .article-part p{\r\n  margin:0 0 20px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.88;\r\n}\r\n\r\n.iso13849-s06 .article-part p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   EXAMPLE ASSUMPTION\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .assumption{\r\n  max-width:800px;\r\n\r\n  margin-top:39px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s06 .assumption .label{\r\n  display:block;\r\n\r\n  margin-bottom:7px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s06 .assumption strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s06 .assumption p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   PROCESS\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .process{\r\n  max-width:800px;\r\n\r\n  margin-top:31px;\r\n\r\n  counter-reset:exampleStep;\r\n}\r\n\r\n.iso13849-s06 .process-step{\r\n  position:relative;\r\n\r\n  margin-left:19px;\r\n\r\n  padding:0 0 34px 38px;\r\n\r\n  border-left:1px solid #ced9df;\r\n\r\n  counter-increment:exampleStep;\r\n}\r\n\r\n.iso13849-s06 .process-step:last-child{\r\n  padding-bottom:0;\r\n\r\n  border-left-color:transparent;\r\n}\r\n\r\n.iso13849-s06 .process-step::before{\r\n  content:counter(exampleStep);\r\n\r\n  position:absolute;\r\n\r\n  left:-19px;\r\n  top:-2px;\r\n\r\n  display:flex;\r\n  align-items:center;\r\n  justify-content:center;\r\n\r\n  width:37px;\r\n  height:37px;\r\n\r\n  background:#ffffff;\r\n\r\n  border:1px solid #9bcfe8;\r\n  border-radius:50%;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:12px;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s06 .process-step h4{\r\n  margin:0 0 7px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:18px;\r\n  line-height:1.45;\r\n  font-weight:800;\r\n}\r\n\r\n.iso13849-s06 .process-step p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n.iso13849-s06 .process-step p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   FUNCTION PARTS\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .function-list{\r\n  margin:20px 0 3px;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n}\r\n\r\n.iso13849-s06 .function-list li{\r\n  position:relative;\r\n\r\n  padding:18px 0 18px 91px;\r\n\r\n  border-top:1px solid var(--line);\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n.iso13849-s06 .function-list li:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s06 .function-label{\r\n  position:absolute;\r\n\r\n  left:0;\r\n  top:19px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.06em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   DATA PATHS\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .data-list{\r\n  margin:23px 0 0;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n}\r\n\r\n.iso13849-s06 .data-item{\r\n  padding:22px 0;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s06 .data-item:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s06 .data-item strong{\r\n  display:block;\r\n\r\n  margin-bottom:7px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s06 .data-item p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   EDITORIAL NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .editorial-note{\r\n  max-width:800px;\r\n\r\n  margin-top:40px;\r\n  padding:26px 29px;\r\n\r\n  background:var(--soft);\r\n}\r\n\r\n.iso13849-s06 .editorial-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s06 .editorial-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s06 .editorial-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   SISTEMA NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .sistema-note{\r\n  max-width:800px;\r\n\r\n  margin-top:38px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s06 .sistema-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s06 .sistema-note p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TAKEAWAY\r\n========================================================= *\/\r\n\r\n.iso13849-s06 .takeaway{\r\n  max-width:800px;\r\n\r\n  margin-top:47px;\r\n  padding-top:28px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s06 .takeaway strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-s06 .takeaway p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s06 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s06 .function-list li{\r\n    padding-left:0;\r\n    padding-top:50px;\r\n  }\r\n\r\n  .iso13849-s06 .function-label{\r\n    top:17px;\r\n  }\r\n\r\n  .iso13849-s06 .editorial-note{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s06\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Worked Example\r\n    <\/div>\r\n\r\n    <h2>\r\n      A Generic Example:\r\n      From PLr to an Evaluated Safety Function\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      A simplified example helps show how risk assessment, safety-function\r\n      definition, subsystem data and Performance Level evaluation fit\r\n      together without tying the process to a particular product.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        Consider a machine with hazardous motion located behind an\r\n        interlocked access guard. Opening the guard while hazardous motion\r\n        is possible requires a safety-related control response.\r\n      <\/p>\r\n\r\n      <p>\r\n        For this example only, assume that the machinery risk assessment and\r\n        any applicable machine-specific requirements have established\r\n        <strong>PLr d<\/strong> for the relevant safety function.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <aside class=\"assumption\">\r\n\r\n      <span class=\"label\">\r\n        Important assumption\r\n      <\/span>\r\n\r\n      <strong>\r\n        PLr d is used here only to demonstrate the evaluation process.\r\n      <\/strong>\r\n\r\n      <p>\r\n        This example does not mean that every interlocked guard, access door\r\n        or hazardous-motion application requires PL d. The actual PLr must\r\n        be established for the specific safety function and machinery risk.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         STEP-BY-STEP\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Step 1 \u2014 Define the safety function\r\n      <\/h3>\r\n\r\n      <p>\r\n        Before carrying out reliability calculations, the intended behaviour\r\n        needs to be defined clearly.\r\n      <\/p>\r\n\r\n      <p>\r\n        A simplified safety-function description for this example might be:\r\n      <\/p>\r\n\r\n      <p>\r\n        <strong>\r\n          When the access guard is opened, hazardous machine motion shall\r\n          be brought to or maintained in the defined safe state in accordance\r\n          with the specified response requirements.\r\n        <\/strong>\r\n      <\/p>\r\n\r\n      <p>\r\n        A real Safety Requirements Specification would contain additional\r\n        information such as operating modes, triggering conditions, safe\r\n        state, required response time, reset and restart behaviour, fault\r\n        reaction and relevant interfaces.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Step 2 \u2014 Identify the parts that implement the safety function\r\n      <\/h3>\r\n\r\n      <p>\r\n        For explanation purposes, many safety functions can be understood\r\n        using the familiar input\u2013logic\u2013output sequence:\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"function-list\">\r\n\r\n        <li>\r\n\r\n          <span class=\"function-label\">\r\n            Input\r\n          <\/span>\r\n\r\n          Detect that the access guard is no longer in the condition required\r\n          for hazardous machine operation.\r\n\r\n        <\/li>\r\n\r\n\r\n        <li>\r\n\r\n          <span class=\"function-label\">\r\n            Logic\r\n          <\/span>\r\n\r\n          Evaluate the safety-related input and issue the required\r\n          safety-related control response.\r\n\r\n        <\/li>\r\n\r\n\r\n        <li>\r\n\r\n          <span class=\"function-label\">\r\n            Output\r\n          <\/span>\r\n\r\n          Act on the machine so that hazardous motion is stopped or prevented\r\n          in accordance with the defined safety function.\r\n\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"editorial-note\">\r\n\r\n      <strong>\r\n        Input, logic and output are a conceptual description \u2014 not a rule\r\n        requiring three separate physical devices.\r\n      <\/strong>\r\n\r\n      <p>\r\n        A real implementation may contain several subsystems, integrated\r\n        functions or different technologies. ISO 13849-1:2023 focuses on the\r\n        safety function as a combination of the subsystems that actually\r\n        contribute to it.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         SUBSYSTEM DATA\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Step 3 \u2014 Determine how each subsystem is evaluated\r\n      <\/h3>\r\n\r\n      <p>\r\n        Not every subsystem has to be evaluated in exactly the same way.\r\n        The available safety-related data depends on whether the subsystem\r\n        is being designed by the machine builder or has already been\r\n        evaluated and validated by its manufacturer.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"data-list\">\r\n\r\n        <div class=\"data-item\">\r\n\r\n          <strong>\r\n            Self-developed subsystem\r\n          <\/strong>\r\n\r\n          <p>\r\n            Where the machine manufacturer or integrator develops the\r\n            subsystem architecture, the ISO 13849 evaluation can require\r\n            parameters such as Category, MTTF<sub>d<\/sub>,\r\n            DC<sub>avg<\/sub>, CCF and the relevant qualitative\r\n            requirements.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"data-item\">\r\n\r\n          <strong>\r\n            Previously evaluated or manufacturer-validated subsystem\r\n          <\/strong>\r\n\r\n          <p>\r\n            A subsystem can already have documented safety-related\r\n            characteristics such as PL capability and PFH together with\r\n            defined conditions and limitations of use. Those data can be\r\n            incorporated into the evaluation of the overall safety function\r\n            in accordance with the applicable standard and the\r\n            manufacturer&#8217;s documentation.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/div>\r\n\r\n      <p>\r\n        This distinction is important. Engineers should not automatically\r\n        open every validated subsystem and invent new internal Category,\r\n        MTTF<sub>d<\/sub> or DC<sub>avg<\/sub> values when the subsystem is\r\n        intended to be used through its declared safety-related data.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         COMBINATION\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Step 4 \u2014 Evaluate the complete safety function\r\n      <\/h3>\r\n\r\n      <p>\r\n        The safety function is then evaluated as the combination of the\r\n        contributing subsystems.\r\n      <\/p>\r\n\r\n      <p>\r\n        Their dangerous-failure contributions, safety-related capabilities,\r\n        architecture and applicable qualitative requirements need to be\r\n        considered using the ISO 13849 methodology.\r\n      <\/p>\r\n\r\n      <p>\r\n        It is not sufficient to identify the subsystem with the highest\r\n        individual PL and apply that rating to the entire function.\r\n        Likewise, a strong input subsystem cannot compensate automatically\r\n        for inadequate performance elsewhere in the safety-related chain.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         COMPARE WITH PLr\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Step 5 \u2014 Compare the achieved PL with PLr\r\n      <\/h3>\r\n\r\n      <p>\r\n        After the relevant quantitative and qualitative requirements have\r\n        been evaluated, the achieved Performance Level is compared with the\r\n        required Performance Level defined in the Safety Requirements\r\n        Specification.\r\n      <\/p>\r\n\r\n      <p>\r\n        For this example:\r\n      <\/p>\r\n\r\n      <p>\r\n        <strong>\r\n          Required PLr = d\r\n        <\/strong>\r\n      <\/p>\r\n\r\n      <p>\r\n        The completed safety-related control function therefore needs to\r\n        demonstrate an achieved Performance Level sufficient for that\r\n        requirement.\r\n      <\/p>\r\n\r\n      <p>\r\n        A calculation that produces a lower achieved PL means that the\r\n        design does not satisfy the assumed PLr and needs to be reconsidered.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         SISTEMA\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Step 6 \u2014 Use calculation tools where appropriate\r\n      <\/h3>\r\n\r\n      <p>\r\n        Engineering tools can make the evaluation easier, particularly when\r\n        a safety function contains several subsystems or detailed reliability\r\n        data.\r\n      <\/p>\r\n\r\n      <p>\r\n        SISTEMA, provided by the German Institute for Occupational Safety\r\n        and Health (IFA), supports ISO 13849 evaluation by modelling\r\n        safety-related structures and calculating values including the\r\n        attained Performance Level.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <aside class=\"sistema-note\">\r\n\r\n      <strong>\r\n        SISTEMA is useful, but ISO 13849 does not become \u201ca SISTEMA\r\n        calculation.\u201d\r\n      <\/strong>\r\n\r\n      <p>\r\n        The tool supports the engineering evaluation. It does not determine\r\n        the machinery hazards, define the safety function automatically,\r\n        prove that the input data are correct, or replace verification and\r\n        validation of the implemented system.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         VERIFICATION AND VALIDATION\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Step 7 \u2014 Verification and validation still follow\r\n      <\/h3>\r\n\r\n      <p>\r\n        Reaching the required calculated PL is not the end of the process.\r\n      <\/p>\r\n\r\n      <p>\r\n        The design needs to be verified against its specified requirements,\r\n        and the implemented safety function needs to be validated to confirm\r\n        that it performs as intended under the relevant operating and fault\r\n        conditions.\r\n      <\/p>\r\n\r\n      <p>\r\n        This includes more than reliability mathematics. The real\r\n        implementation can involve wiring, configuration, software,\r\n        interfaces, fault reaction, stopping behaviour and restart behaviour\r\n        that need to be checked as part of the complete safety argument.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         DO NOT INFER CATEGORY\r\n    ====================================================== -->\r\n\r\n    <div class=\"editorial-note\">\r\n\r\n      <strong>\r\n        Do not assign a Category or PL simply by counting devices or\r\n        channels.\r\n      <\/strong>\r\n\r\n      <p>\r\n        Two switches, two outputs or two contactors do not automatically\r\n        establish Category 3, Category 4, PL d or PL e. The architecture,\r\n        fault behaviour, diagnostic coverage, reliability, CCF measures and\r\n        the other applicable requirements must support the claimed result.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         TAKEAWAY\r\n    ====================================================== -->\r\n\r\n    <div class=\"takeaway\">\r\n\r\n      <strong>\r\n        Key takeaway\r\n      <\/strong>\r\n\r\n      <p>\r\n        Start with the hazard and the defined safety function, establish\r\n        PLr, identify the contributing subsystems and their valid\r\n        safety-related data, evaluate the complete function, and then verify\r\n        and validate the implementation. Product ratings and software\r\n        calculations support that process; they do not replace it.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 07 \u2014 PERFORMANCE LEVEL VS SIL\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s07,\r\n.iso13849-s07 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s07{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n  background:#f8fafb;\r\n\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s07 .inner{\r\n  max-width:880px;\r\n  margin:0 auto;\r\n  padding:78px 28px 84px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   HEADER\r\n========================================================= *\/\r\n\r\n.iso13849-s07 .eyebrow{\r\n  display:flex;\r\n  align-items:center;\r\n  gap:10px;\r\n\r\n  margin-bottom:15px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:12px;\r\n  line-height:1.4;\r\n  font-weight:800;\r\n\r\n  letter-spacing:.1em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s07 .eyebrow::before{\r\n  content:\"07\";\r\n\r\n  color:var(--blue);\r\n\r\n  font-size:12px;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s07 .eyebrow::after{\r\n  content:\"\";\r\n\r\n  width:34px;\r\n  height:1px;\r\n\r\n  background:#9fd8f3;\r\n}\r\n\r\n.iso13849-s07 h2{\r\n  max-width:820px;\r\n\r\n  margin:0;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:clamp(31px,4vw,43px);\r\n  line-height:1.16;\r\n  font-weight:850;\r\n\r\n  letter-spacing:-.025em;\r\n}\r\n\r\n.iso13849-s07 .lead{\r\n  max-width:800px;\r\n\r\n  margin:22px 0 0;\r\n\r\n  color:#465865;\r\n\r\n  font-size:18px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   BODY\r\n========================================================= *\/\r\n\r\n.iso13849-s07 .copy{\r\n  max-width:800px;\r\n  margin-top:35px;\r\n}\r\n\r\n.iso13849-s07 .copy p{\r\n  margin:0 0 22px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.9;\r\n}\r\n\r\n.iso13849-s07 strong{\r\n  color:var(--navy);\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   ARTICLE PART\r\n========================================================= *\/\r\n\r\n.iso13849-s07 .article-part{\r\n  max-width:800px;\r\n\r\n  margin-top:52px;\r\n  padding-top:40px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s07 .article-part h3{\r\n  margin:0 0 17px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:25px;\r\n  line-height:1.35;\r\n  font-weight:820;\r\n\r\n  letter-spacing:-.015em;\r\n}\r\n\r\n.iso13849-s07 .article-part p{\r\n  margin:0 0 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COMPARISON TABLE\r\n========================================================= *\/\r\n\r\n.iso13849-s07 .table-wrap{\r\n  max-width:800px;\r\n\r\n  margin-top:27px;\r\n\r\n  overflow-x:auto;\r\n\r\n  border-top:1px solid #cad5db;\r\n  border-bottom:1px solid #cad5db;\r\n}\r\n\r\n.iso13849-s07 table{\r\n  width:100%;\r\n  min-width:720px;\r\n\r\n  border-collapse:collapse;\r\n}\r\n\r\n.iso13849-s07 th{\r\n  padding:15px 17px;\r\n\r\n  border-bottom:2px solid #cad5db;\r\n\r\n  color:#536571;\r\n\r\n  text-align:left;\r\n\r\n  font-size:11px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.055em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s07 td{\r\n  padding:19px 17px;\r\n\r\n  border-bottom:1px solid #e5ebee;\r\n\r\n  color:#40535f;\r\n\r\n  font-size:14px;\r\n  line-height:1.72;\r\n\r\n  vertical-align:top;\r\n}\r\n\r\n.iso13849-s07 tbody tr:last-child td{\r\n  border-bottom:0;\r\n}\r\n\r\n.iso13849-s07 .pl{\r\n  color:var(--navy);\r\n\r\n  font-size:17px;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s07 .pfh{\r\n  font-family:\r\n    ui-monospace,\r\n    SFMono-Regular,\r\n    Menlo,\r\n    Monaco,\r\n    Consolas,\r\n    \"Liberation Mono\",\r\n    monospace;\r\n\r\n  font-size:13px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   EDITORIAL NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s07 .editorial-note{\r\n  max-width:800px;\r\n\r\n  margin-top:39px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s07 .editorial-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s07 .editorial-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s07 .editorial-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   PLAIN LIST\r\n========================================================= *\/\r\n\r\n.iso13849-s07 .plain-list{\r\n  margin:18px 0 4px;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n}\r\n\r\n.iso13849-s07 .plain-list li{\r\n  position:relative;\r\n\r\n  margin:10px 0;\r\n  padding-left:20px;\r\n\r\n  color:#455864;\r\n\r\n  font-size:14px;\r\n  line-height:1.76;\r\n}\r\n\r\n.iso13849-s07 .plain-list li::before{\r\n  content:\"\";\r\n\r\n  position:absolute;\r\n\r\n  left:2px;\r\n  top:.73em;\r\n\r\n  width:5px;\r\n  height:5px;\r\n\r\n  background:var(--blue);\r\n\r\n  border-radius:50%;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   STANDARD NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s07 .standard-note{\r\n  max-width:800px;\r\n\r\n  margin-top:40px;\r\n  padding:25px 28px;\r\n\r\n  background:#ffffff;\r\n}\r\n\r\n.iso13849-s07 .standard-note .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s07 .standard-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s07 .standard-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TAKEAWAY\r\n========================================================= *\/\r\n\r\n.iso13849-s07 .takeaway{\r\n  max-width:800px;\r\n\r\n  margin-top:47px;\r\n  padding-top:28px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s07 .takeaway strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-s07 .takeaway p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s07 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s07\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Functional Safety Frameworks\r\n    <\/div>\r\n\r\n    <h2>\r\n      Performance Level vs SIL:\r\n      How Should They Be Compared?\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      ISO 13849-1 uses Performance Levels, while IEC 62061 uses Safety\r\n      Integrity Levels. Both frameworks use PFH when evaluating dangerous\r\n      random hardware failure, but PL and SIL should not be treated as\r\n      interchangeable labels.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        Machinery engineers commonly encounter both\r\n        <strong>ISO 13849-1<\/strong> and <strong>IEC 62061<\/strong>.\r\n        The two standards address functional safety of machinery control\r\n        systems from different methodological perspectives.\r\n      <\/p>\r\n\r\n      <p>\r\n        Their quantitative results can be compared because both use the\r\n        average frequency of dangerous failure per hour, or PFH, as an\r\n        important reliability measure.\r\n      <\/p>\r\n\r\n      <p>\r\n        That common metric is useful, but it should not be stretched into\r\n        the claim that every PL has a completely identical SIL equivalent.\r\n        The surrounding architecture, design rules, systematic requirements\r\n        and validation methodology remain standard-specific.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         DEFINITIONS\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        PL and SIL belong to different methodologies\r\n      <\/h3>\r\n\r\n\r\n      <div class=\"definition-list\">\r\n\r\n        <div class=\"definition-item\">\r\n\r\n          <h4>\r\n            Performance Level \u2014 ISO 13849-1\r\n          <\/h4>\r\n\r\n          <p>\r\n            ISO 13849-1 uses PL a through PL e and combines quantitative\r\n            reliability with designated architectures, diagnostic coverage,\r\n            MTTF<sub>d<\/sub>, common-cause-failure measures and requirements\r\n            relating to systematic integrity.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"definition-item\">\r\n\r\n          <h4>\r\n            Safety Integrity Level \u2014 IEC 62061\r\n          <\/h4>\r\n\r\n          <p>\r\n            IEC 62061 uses SIL 1 through SIL 3 for machinery safety-related\r\n            control functions. Its methodology evaluates probabilistic\r\n            hardware integrity together with architectural constraints and\r\n            systematic safety integrity.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         PFH COMPARISON\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Comparing the quantitative PFH ranges\r\n      <\/h3>\r\n\r\n      <p>\r\n        The table below is best read as a\r\n        <strong>PFH correspondence guide<\/strong>, not as a universal\r\n        conversion table between two complete standards.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"table-wrap\">\r\n\r\n        <table>\r\n\r\n          <thead>\r\n\r\n            <tr>\r\n\r\n              <th>\r\n                ISO 13849 PL\r\n              <\/th>\r\n\r\n              <th>\r\n                ISO 13849-1:2023 PFH\r\n              <\/th>\r\n\r\n              <th>\r\n                IEC 62061 Context\r\n              <\/th>\r\n\r\n            <\/tr>\r\n\r\n          <\/thead>\r\n\r\n\r\n          <tbody>\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL a\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                1 \u00d7 10<sup>\u22125<\/sup>\r\n                \u2264 PFH\r\n                &lt;\r\n                1 \u00d7 10<sup>\u22124<\/sup>\r\n              <\/td>\r\n\r\n              <td>\r\n                No direct SIL 1\u20133 correspondence across the complete\r\n                PL a range.\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL b\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                3 \u00d7 10<sup>\u22126<\/sup>\r\n                \u2264 PFH\r\n                &lt;\r\n                1 \u00d7 10<sup>\u22125<\/sup>\r\n              <\/td>\r\n\r\n              <td>\r\n                Falls within the IEC 62061 SIL 1 PFH band.\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL c\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                1 \u00d7 10<sup>\u22126<\/sup>\r\n                \u2264 PFH\r\n                &lt;\r\n                3 \u00d7 10<sup>\u22126<\/sup>\r\n              <\/td>\r\n\r\n              <td>\r\n                Falls within the IEC 62061 SIL 1 PFH band.\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL d\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                1 \u00d7 10<sup>\u22127<\/sup>\r\n                \u2264 PFH\r\n                &lt;\r\n                1 \u00d7 10<sup>\u22126<\/sup>\r\n              <\/td>\r\n\r\n              <td>\r\n                Corresponds quantitatively to the IEC 62061 SIL 2\r\n                PFH band.\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"pl\">\r\n                PL e\r\n              <\/td>\r\n\r\n              <td class=\"pfh\">\r\n                PFH\r\n                &lt;\r\n                1 \u00d7 10<sup>\u22127<\/sup>\r\n              <\/td>\r\n\r\n              <td>\r\n                Corresponds to the highest machinery safety-integrity\r\n                region associated with SIL 3, while the IEC 62061 SIL 3\r\n                PFH band is normally expressed as\r\n                1 \u00d7 10<sup>\u22128<\/sup> \u2264 PFH &lt; 1 \u00d7 10<sup>\u22127<\/sup>.\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n          <\/tbody>\r\n\r\n        <\/table>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         IMPORTANT 2023 DETAIL\r\n    ====================================================== -->\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        A subtle but important ISO 13849-1:2023 detail:\r\n        PL e is defined simply as PFH &lt; 10<sup>\u22127<\/sup>.\r\n      <\/strong>\r\n\r\n      <p>\r\n        Earlier comparison tables are often written as though PL e itself\r\n        were limited to the interval from 10<sup>\u22128<\/sup> to\r\n        10<sup>\u22127<\/sup> per hour. The current ISO 13849-1:2023 Table 2\r\n        instead specifies PL e as PFH below 10<sup>\u22127<\/sup>.\r\n      <\/p>\r\n\r\n      <p>\r\n        This is one reason it is better to describe PL\/SIL relationships\r\n        as correspondence between safety-integrity regions and PFH\r\n        requirements rather than as perfect one-to-one equivalence.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         NOT FULL EQUIVALENCE\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        \u201cPL d equals SIL 2\u201d is useful shorthand \u2014 but incomplete\r\n      <\/h3>\r\n\r\n      <p>\r\n        PL d and SIL 2 occupy the same quantitative PFH interval, so the\r\n        shorthand comparison is useful when discussing dangerous random\r\n        hardware failure.\r\n      <\/p>\r\n\r\n      <p>\r\n        It does not mean that a system designed and evaluated under\r\n        ISO 13849-1 can simply be relabelled as an IEC 62061 SIL 2 system,\r\n        or vice versa.\r\n      <\/p>\r\n\r\n      <p>\r\n        Each standard has requirements governing matters such as subsystem\r\n        architecture, hardware fault tolerance, diagnostics, systematic\r\n        failures, software, verification and validation. Those requirements\r\n        remain part of the applicable methodology.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         CATEGORY\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Category is not a third equivalent scale\r\n      <\/h3>\r\n\r\n      <p>\r\n        ISO 13849 Categories B, 1, 2, 3 and 4 describe designated\r\n        architectures and fault behaviour. They do not form another\r\n        integrity scale that can be placed beside PL and SIL in a simple\r\n        three-column conversion chart.\r\n      <\/p>\r\n\r\n      <p>\r\n        For example, the statement:\r\n      <\/p>\r\n\r\n      <p>\r\n        <strong>\r\n          Category 3 = PL d = SIL 2\r\n        <\/strong>\r\n      <\/p>\r\n\r\n      <p>\r\n        is an oversimplification.\r\n      <\/p>\r\n\r\n      <p>\r\n        Category 3 can be part of a design that achieves PL d, but the\r\n        achieved PL also depends on reliability data, diagnostic coverage,\r\n        common-cause-failure measures and fulfilment of the other applicable\r\n        ISO 13849 requirements.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         USING PRE-DESIGNED SUBSYSTEMS\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Cross-standard subsystem use is possible \u2014 but controlled\r\n      <\/h3>\r\n\r\n      <p>\r\n        Modern machinery safety design can combine previously validated\r\n        subsystems developed under different functional-safety standards.\r\n        ISO 13849-1:2023 explicitly recognises previously validated\r\n        subsystems according to IEC 62061, the IEC 61508 series and relevant\r\n        safety-related product standards.\r\n      <\/p>\r\n\r\n      <p>\r\n        Where SIL-based subsystems are incorporated into an ISO 13849\r\n        safety function, their PFH and integrity capability can be used\r\n        within the conditions defined by the standard. This does not mean\r\n        that an ISO 13849 Category must always be assigned to the imported\r\n        subsystem.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         CHOOSING FRAMEWORK\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        ISO 13849 or IEC 62061?\r\n      <\/h3>\r\n\r\n      <p>\r\n        The appropriate framework depends on the machinery application,\r\n        applicable standards, technologies involved, engineering approach\r\n        and the safety lifecycle adopted for the project.\r\n      <\/p>\r\n\r\n      <p>\r\n        It is no longer accurate to reduce the choice to\r\n        \u201cISO 13849 for mechanical systems and IEC 62061 for electrical\r\n        systems.\u201d Both standards now support broad machinery control-system\r\n        technologies and can be used in sophisticated functional-safety\r\n        designs.\r\n      <\/p>\r\n\r\n      <p>\r\n        Whichever methodology is selected, it should be applied coherently\r\n        and documented clearly.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         STANDARD CONTEXT\r\n    ====================================================== -->\r\n\r\n    <div class=\"standard-note\">\r\n\r\n      <span class=\"label\">\r\n        Current standards context\r\n      <\/span>\r\n\r\n      <p>\r\n        ISO 13849-1:2023 is the current fourth edition of Part 1.\r\n        IEC 62061:2021 is the current base edition of the machinery\r\n        functional-safety standard, with subsequent amendments.\r\n      <\/p>\r\n\r\n      <p>\r\n        In IEC 62061, the dangerous random hardware failure bands for\r\n        machinery are commonly expressed as SIL 1:\r\n        10<sup>\u22126<\/sup> to &lt;10<sup>\u22125<\/sup>,\r\n        SIL 2: 10<sup>\u22127<\/sup> to &lt;10<sup>\u22126<\/sup>,\r\n        and SIL 3: 10<sup>\u22128<\/sup> to &lt;10<sup>\u22127<\/sup> per hour.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         SUMMARY\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Three points worth remembering\r\n      <\/h3>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          <strong>PL and SIL can be compared through PFH,<\/strong>\r\n          but the two complete methodologies are not interchangeable.\r\n        <\/li>\r\n\r\n        <li>\r\n          <strong>PL d and SIL 2 have a particularly direct quantitative\r\n          PFH correspondence,<\/strong> while PL e should be read using the\r\n          current ISO 13849-1:2023 definition of PFH &lt;10<sup>\u22127<\/sup>.\r\n        <\/li>\r\n\r\n        <li>\r\n          <strong>Category is an ISO 13849 architectural concept,<\/strong>\r\n          not an additional SIL\/PL conversion scale.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         TAKEAWAY\r\n    ====================================================== -->\r\n\r\n    <div class=\"takeaway\">\r\n\r\n      <strong>\r\n        Key takeaway\r\n      <\/strong>\r\n\r\n      <p>\r\n        Use PFH correspondence to understand the relationship between\r\n        Performance Level and Safety Integrity Level, but follow the design,\r\n        calculation, verification and validation requirements of the\r\n        functional-safety standard actually being applied.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 08 \u2014 IEC 61496 TYPE 2 \/ TYPE 3 \/ TYPE 4\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s08,\r\n.iso13849-s08 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s08{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n  background:#f8fafb;\r\n\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s08 .inner{\r\n  max-width:880px;\r\n  margin:0 auto;\r\n  padding:78px 28px 84px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   HEADER\r\n========================================================= *\/\r\n\r\n.iso13849-s08 .eyebrow{\r\n  display:flex;\r\n  align-items:center;\r\n  gap:10px;\r\n\r\n  margin-bottom:15px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:12px;\r\n  line-height:1.4;\r\n  font-weight:800;\r\n\r\n  letter-spacing:.1em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s08 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=========================================================\r\n   EDITORIAL NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s08 .editorial-note{\r\n  max-width:800px;\r\n\r\n  margin-top:39px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s08 .editorial-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s08 .editorial-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s08 .editorial-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   PLAIN LIST\r\n========================================================= *\/\r\n\r\n.iso13849-s08 .plain-list{\r\n  margin:18px 0 4px;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n}\r\n\r\n.iso13849-s08 .plain-list li{\r\n  position:relative;\r\n\r\n  margin:10px 0;\r\n  padding-left:20px;\r\n\r\n  color:#455864;\r\n\r\n  font-size:14px;\r\n  line-height:1.76;\r\n}\r\n\r\n.iso13849-s08 .plain-list li::before{\r\n  content:\"\";\r\n\r\n  position:absolute;\r\n\r\n  left:2px;\r\n  top:.73em;\r\n\r\n  width:5px;\r\n  height:5px;\r\n\r\n  background:var(--blue);\r\n\r\n  border-radius:50%;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   EXAMPLE\r\n========================================================= *\/\r\n\r\n.iso13849-s08 .example{\r\n  max-width:800px;\r\n\r\n  margin-top:38px;\r\n  padding:26px 29px;\r\n\r\n  background:#ffffff;\r\n}\r\n\r\n.iso13849-s08 .example .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s08 .example strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s08 .example p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s08 .example p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   STANDARD NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s08 .standard-note{\r\n  max-width:800px;\r\n\r\n  margin-top:40px;\r\n  padding:25px 28px;\r\n\r\n  background:var(--soft);\r\n}\r\n\r\n.iso13849-s08 .standard-note .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s08 .standard-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s08 .standard-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TAKEAWAY\r\n========================================================= *\/\r\n\r\n.iso13849-s08 .takeaway{\r\n  max-width:800px;\r\n\r\n  margin-top:47px;\r\n  padding-top:28px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s08 .takeaway strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-s08 .takeaway p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s08 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s08 .example{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s08\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Electro-Sensitive Protective Equipment\r\n    <\/div>\r\n\r\n    <h2>\r\n      IEC 61496 Type 2, Type 3 and Type 4:\r\n      How Do They Relate to PL and SIL?\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      IEC 61496 classifies electro-sensitive protective equipment by Type.\r\n      These Type classes define safety-related capability of the protective\r\n      equipment, but they do not determine the achieved PL or SIL of the\r\n      complete machine safety function.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        <strong>IEC 61496-1<\/strong> provides general requirements and\r\n        tests for electro-sensitive protective equipment, commonly\r\n        abbreviated <strong>ESPE<\/strong>.\r\n      <\/p>\r\n\r\n      <p>\r\n        Different sensing technologies are then addressed by subsequent\r\n        parts of the IEC 61496 series. For example, active opto-electronic\r\n        protective devices \u2014 AOPDs \u2014 used for applications such as safety\r\n        light curtains are addressed by IEC 61496-2.\r\n      <\/p>\r\n\r\n      <p>\r\n        One of the most useful aspects of the Type classification is that\r\n        it establishes the maximum safety-integrity capability for which\r\n        an ESPE Type can be used.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         TYPE \/ PL \/ SIL TABLE\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Type class and application capability\r\n      <\/h3>\r\n\r\n      <p>\r\n        The relationship is best expressed using\r\n        <strong>\u201cup to\u201d<\/strong> rather than treating Type, PL and SIL\r\n        as interchangeable labels.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"table-wrap\">\r\n\r\n        <table>\r\n\r\n          <thead>\r\n\r\n            <tr>\r\n\r\n              <th>\r\n                IEC 61496 Type\r\n              <\/th>\r\n\r\n              <th>\r\n                ISO 13849 Application Capability\r\n              <\/th>\r\n\r\n              <th>\r\n                IEC 62061 Application Capability\r\n              <\/th>\r\n\r\n            <\/tr>\r\n\r\n          <\/thead>\r\n\r\n\r\n          <tbody>\r\n\r\n            <tr>\r\n\r\n              <td class=\"type\">\r\n                Type 2\r\n              <\/td>\r\n\r\n              <td>\r\n                <span class=\"capability\">\r\n                  Up to PL c\r\n                <\/span>\r\n              <\/td>\r\n\r\n              <td>\r\n                Up to SIL 1 \/ SIL CL 1\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"type\">\r\n                Type 3\r\n              <\/td>\r\n\r\n              <td>\r\n                <span class=\"capability\">\r\n                  Up to PL d\r\n                <\/span>\r\n              <\/td>\r\n\r\n              <td>\r\n                Up to SIL 2 \/ SIL CL 2\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"type\">\r\n                Type 4\r\n              <\/td>\r\n\r\n              <td>\r\n                <span class=\"capability\">\r\n                  Up to PL e\r\n                <\/span>\r\n              <\/td>\r\n\r\n              <td>\r\n                Up to SIL 3 \/ SIL CL 3\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n          <\/tbody>\r\n\r\n        <\/table>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         CRITICAL DISTINCTION\r\n    ====================================================== -->\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        \u201cType 4\u201d does not mean that the complete safety function is PL e.\r\n      <\/strong>\r\n\r\n      <p>\r\n        Type 4 means that the ESPE has the safety-related capability\r\n        required for use in applications up to PL e \/ SIL 3, subject to\r\n        the applicable standards and conditions of use.\r\n      <\/p>\r\n\r\n      <p>\r\n        The logic subsystem, output subsystem, interfaces, wiring,\r\n        architecture, reliability data and other parts of the complete\r\n        safety function must still support the required Performance Level.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         TYPE 3\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Why is Type 3 important?\r\n      <\/h3>\r\n\r\n      <p>\r\n        Earlier editions of the IEC 61496 framework were commonly\r\n        associated with Type 2 and Type 4 ESPEs. The fourth edition of\r\n        IEC 61496-1, published in 2020, introduced Type 3 as an additional\r\n        class.\r\n      <\/p>\r\n\r\n      <p>\r\n        Type 3 provides capability for applications up to\r\n        <strong>PL d \/ SIL 2<\/strong>. This fills the gap between the\r\n        maximum application capability of Type 2 and Type 4.\r\n      <\/p>\r\n\r\n      <p>\r\n        It also demonstrates why Type selection should follow the required\r\n        performance of the safety function rather than the assumption that\r\n        the highest Type must always be selected.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         EXAMPLE\r\n    ====================================================== -->\r\n\r\n    <div class=\"example\">\r\n\r\n      <span class=\"label\">\r\n        Example\r\n      <\/span>\r\n\r\n      <strong>\r\n        Assume a defined safety function has PLr d.\r\n      <\/strong>\r\n\r\n      <p>\r\n        A Type 2 ESPE has application capability only up to PL c and\r\n        therefore cannot provide the required ESPE capability for that\r\n        PLr d safety function.\r\n      <\/p>\r\n\r\n      <p>\r\n        A Type 3 ESPE has capability up to PL d and can therefore be\r\n        suitable from the ESPE performance-class perspective.\r\n      <\/p>\r\n\r\n      <p>\r\n        A Type 4 ESPE can also be used because its capability extends up\r\n        to PL e. However, neither Type 3 nor Type 4 automatically proves\r\n        that the complete safety function achieves PL d.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         TYPE IS NOT RESOLUTION\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Type is not the same as resolution or detection capability\r\n      <\/h3>\r\n\r\n      <p>\r\n        A second common misunderstanding is to treat the IEC 61496 Type\r\n        class as though it described the physical detection resolution of\r\n        an ESPE.\r\n      <\/p>\r\n\r\n      <p>\r\n        These are different characteristics.\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          <strong>Type<\/strong> addresses safety-related design,\r\n          fault behaviour and integrity capability.\r\n        <\/li>\r\n\r\n        <li>\r\n          <strong>Detection capability or resolution<\/strong> describes\r\n          the size or characteristic of an object that the sensing system\r\n          is intended to detect.\r\n        <\/li>\r\n\r\n        <li>\r\n          <strong>Protective-field dimensions<\/strong> describe the\r\n          physical sensing area provided by the equipment.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n      <p>\r\n        A particular resolution therefore does not establish whether an\r\n        ESPE is Type 2, Type 3 or Type 4.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         DEVICE VS SYSTEM\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Device capability and system capability are separate questions\r\n      <\/h3>\r\n\r\n      <p>\r\n        When selecting an electro-sensitive protective device, two\r\n        questions should be kept separate.\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          Is the ESPE Type suitable for the required PLr or SIL of the\r\n          application?\r\n        <\/li>\r\n\r\n        <li>\r\n          Does the complete safety-related control function actually\r\n          achieve the required performance after all contributing\r\n          subsystems are evaluated?\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n      <p>\r\n        The first question concerns the capability of the protective\r\n        equipment. The second concerns the complete machine safety function.\r\n      <\/p>\r\n\r\n      <p>\r\n        Passing the first test does not automatically answer the second.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         IEC 61496 SCOPE\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        IEC 61496 does not determine the complete safeguarding layout\r\n      <\/h3>\r\n\r\n      <p>\r\n        IEC 61496 specifies requirements for the protective equipment\r\n        itself and its safety-related performance and interface behaviour.\r\n        It does not, by itself, determine every aspect of how the safeguard\r\n        must be applied to a particular machine.\r\n      <\/p>\r\n\r\n      <p>\r\n        Matters such as the required safety function, machine risk\r\n        assessment, positioning of the protective equipment, safety\r\n        distance and other application-specific measures need to be\r\n        addressed through the relevant machinery safety standards and\r\n        engineering process.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         STANDARD CONTEXT\r\n    ====================================================== -->\r\n\r\n    <div class=\"standard-note\">\r\n\r\n      <span class=\"label\">\r\n        Standards context\r\n      <\/span>\r\n\r\n      <p>\r\n        IEC 61496-1:2020 is the fourth edition of\r\n        <em>Safety of machinery \u2014 Electro-sensitive protective equipment \u2014\r\n        Part 1: General requirements and tests<\/em>.\r\n      <\/p>\r\n\r\n      <p>\r\n        IEC 61496-2:2020 contains particular requirements for equipment\r\n        using active opto-electronic protective devices (AOPDs), the sensing\r\n        principle commonly associated with safety light curtains and\r\n        related optical protective equipment.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         TAKEAWAY\r\n    ====================================================== -->\r\n\r\n    <div class=\"takeaway\">\r\n\r\n      <strong>\r\n        Key takeaway\r\n      <\/strong>\r\n\r\n      <p>\r\n        IEC 61496 Type defines the application capability of the\r\n        electro-sensitive protective equipment: Type 2 up to PL c \/\r\n        SIL 1, Type 3 up to PL d \/ SIL 2, and Type 4 up to PL e \/\r\n        SIL 3. The achieved PL or SIL of the complete safety function\r\n        must still be established separately.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 09 \u2014 VERIFICATION, VALIDATION & SISTEMA\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s09,\r\n.iso13849-s09 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s09{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s09 .inner{\r\n  max-width:880px;\r\n  margin:0 auto;\r\n  padding:78px 28px 84px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   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=========================================================\r\n   EDITORIAL NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s09 .editorial-note{\r\n  max-width:800px;\r\n\r\n  margin-top:39px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s09 .editorial-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s09 .editorial-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s09 .editorial-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   STANDARD STATUS\r\n========================================================= *\/\r\n\r\n.iso13849-s09 .standard-status{\r\n  max-width:800px;\r\n\r\n  margin-top:40px;\r\n  padding:27px 29px;\r\n\r\n  background:var(--soft);\r\n}\r\n\r\n.iso13849-s09 .standard-status .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s09 .standard-status strong{\r\n  display:block;\r\n\r\n  margin-bottom:10px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s09 .standard-status p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s09 .standard-status p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   SISTEMA LIST\r\n========================================================= *\/\r\n\r\n.iso13849-s09 .sistema-list{\r\n  max-width:800px;\r\n  margin-top:24px;\r\n}\r\n\r\n.iso13849-s09 .sistema-item{\r\n  padding:22px 0;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s09 .sistema-item:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s09 .sistema-item strong{\r\n  display:block;\r\n\r\n  margin-bottom:7px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s09 .sistema-item p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   PROCESS LINE\r\n========================================================= *\/\r\n\r\n.iso13849-s09 .process-line{\r\n  max-width:800px;\r\n\r\n  margin-top:32px;\r\n  padding:25px 0;\r\n\r\n  border-top:1px solid var(--line);\r\n  border-bottom:1px solid var(--line);\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:17px;\r\n  line-height:1.75;\r\n  font-weight:800;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TAKEAWAY\r\n========================================================= *\/\r\n\r\n.iso13849-s09 .takeaway{\r\n  max-width:800px;\r\n\r\n  margin-top:47px;\r\n  padding-top:28px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s09 .takeaway strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-s09 .takeaway p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s09 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s09 .standard-status{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s09\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Completing the Safety Process\r\n    <\/div>\r\n\r\n    <h2>\r\n      Verification, Validation and SISTEMA:\r\n      What Does Each One Do?\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      Calculating an achieved Performance Level is important, but the\r\n      calculation is only one part of demonstrating that a safety function\r\n      has been designed and implemented correctly.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        Functional safety requires a traceable connection between the\r\n        original safety requirements, the engineering design, the\r\n        quantitative evaluation and the behaviour of the implemented\r\n        machine.\r\n      <\/p>\r\n\r\n      <p>\r\n        This is why <strong>verification<\/strong>,\r\n        <strong>validation<\/strong> and tools such as\r\n        <strong>SISTEMA<\/strong> should not be treated as interchangeable\r\n        activities.\r\n      <\/p>\r\n\r\n      <p>\r\n        A calculation can show that the numerical and architectural\r\n        assumptions of a design are capable of achieving the required\r\n        Performance Level. It cannot, by itself, prove that the real\r\n        machine has been wired, programmed, configured and integrated\r\n        correctly.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         VERIFICATION VS VALIDATION\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Verification and validation answer different questions\r\n      <\/h3>\r\n\r\n      <p>\r\n        In practical engineering terms, the distinction can be understood\r\n        as follows.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"comparison-wrap\">\r\n\r\n        <table>\r\n\r\n          <thead>\r\n\r\n            <tr>\r\n\r\n              <th>\r\n                Activity\r\n              <\/th>\r\n\r\n              <th>\r\n                Main Question\r\n              <\/th>\r\n\r\n              <th>\r\n                Typical Evidence\r\n              <\/th>\r\n\r\n            <\/tr>\r\n\r\n          <\/thead>\r\n\r\n\r\n          <tbody>\r\n\r\n            <tr>\r\n\r\n              <td class=\"term\">\r\n                Verification\r\n              <\/td>\r\n\r\n              <td>\r\n                Does the design and its evaluation satisfy the requirements\r\n                and design criteria that were specified?\r\n              <\/td>\r\n\r\n              <td>\r\n                Design review, architecture checks, calculations, subsystem\r\n                data, software review and confirmation of the achieved PL.\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n\r\n            <tr>\r\n\r\n              <td class=\"term\">\r\n                Validation\r\n              <\/td>\r\n\r\n              <td>\r\n                Does the implemented safety function actually satisfy the\r\n                specified safety requirements?\r\n              <\/td>\r\n\r\n              <td>\r\n                Analysis and testing of the implemented function, including\r\n                normal operation, relevant fault conditions and specified\r\n                safety behaviour.\r\n              <\/td>\r\n\r\n            <\/tr>\r\n\r\n          <\/tbody>\r\n\r\n        <\/table>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         VERIFICATION\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Verification: checking the engineering result\r\n      <\/h3>\r\n\r\n      <p>\r\n        Verification provides evidence that the safety-related design has\r\n        been developed and evaluated in accordance with the defined\r\n        requirements and the applicable ISO 13849 methodology.\r\n      <\/p>\r\n\r\n      <p>\r\n        Depending on the safety function, verification can include\r\n        confirming:\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          that the safety function and its requirements have been defined\r\n          clearly;\r\n        <\/li>\r\n\r\n        <li>\r\n          that the selected PLr is the requirement being addressed;\r\n        <\/li>\r\n\r\n        <li>\r\n          that subsystem structures and interfaces are represented\r\n          correctly;\r\n        <\/li>\r\n\r\n        <li>\r\n          that manufacturer data and reliability values are being used\r\n          within their stated conditions;\r\n        <\/li>\r\n\r\n        <li>\r\n          that Category, MTTF<sub>d<\/sub>, DC<sub>avg<\/sub>, CCF and other\r\n          relevant parameters have been evaluated where applicable;\r\n        <\/li>\r\n\r\n        <li>\r\n          that software and systematic requirements have been addressed;\r\n          and\r\n        <\/li>\r\n\r\n        <li>\r\n          that the achieved Performance Level is sufficient for the\r\n          required PLr.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n      <p>\r\n        Verification is therefore broader than simply reading the final PL\r\n        value from a calculation tool.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         VALIDATION\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Validation: confirming the implemented safety function\r\n      <\/h3>\r\n\r\n      <p>\r\n        Validation examines whether the implemented safety-related control\r\n        function actually fulfils the specified safety requirements.\r\n      <\/p>\r\n\r\n      <p>\r\n        ISO 13849 validation uses\r\n        <strong>analysis and testing<\/strong>. The two approaches complement\r\n        one another; analysis does not remove the need for appropriate\r\n        functional testing.\r\n      <\/p>\r\n\r\n      <p>\r\n        Depending on the safety function and its specification, validation\r\n        can include examination of:\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          initiation of the required safety action;\r\n        <\/li>\r\n\r\n        <li>\r\n          achievement and maintenance of the defined safe state;\r\n        <\/li>\r\n\r\n        <li>\r\n          response to relevant faults;\r\n        <\/li>\r\n\r\n        <li>\r\n          reset and restart behaviour;\r\n        <\/li>\r\n\r\n        <li>\r\n          operating modes and mode transitions;\r\n        <\/li>\r\n\r\n        <li>\r\n          specified response or stopping times;\r\n        <\/li>\r\n\r\n        <li>\r\n          wiring and interface behaviour;\r\n        <\/li>\r\n\r\n        <li>\r\n          software and parameter settings; and\r\n        <\/li>\r\n\r\n        <li>\r\n          environmental or operating conditions that form part of the\r\n          Safety Requirements Specification.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n    <\/div>\r\n\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        Analysis supplements testing \u2014 it does not simply replace it.\r\n      <\/strong>\r\n\r\n      <p>\r\n        Reliability calculations, schematics and software reviews can reveal\r\n        important design information, while functional tests provide\r\n        evidence about the behaviour of the implemented safety function.\r\n        Both forms of evidence can be necessary within the validation\r\n        process.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         ISO 13849-1 \/ PART 2\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        What changed with validation in ISO 13849-1:2023?\r\n      <\/h3>\r\n\r\n      <p>\r\n        Earlier editions were often used together with ISO 13849-2 for the\r\n        detailed validation process.\r\n      <\/p>\r\n\r\n      <p>\r\n        In ISO 13849-1:2023, the normative validation requirements were\r\n        revised and incorporated into\r\n        <strong>Clause 10 of Part 1<\/strong>. This makes validation a more\r\n        visible part of the same safety-function design lifecycle covered\r\n        by ISO 13849-1.\r\n      <\/p>\r\n\r\n      <p>\r\n        The change also strengthens the relationship between the Safety\r\n        Requirements Specification and the later validation process:\r\n        validation needs a defined set of requirements against which the\r\n        implemented safety function can be examined.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"standard-status\">\r\n\r\n      <span class=\"label\">\r\n        Current standards status\r\n      <\/span>\r\n\r\n      <strong>\r\n        ISO 13849-2:2012 has not simply disappeared.\r\n      <\/strong>\r\n\r\n      <p>\r\n        ISO 13849-2:2012 remains a published ISO standard at present.\r\n        It specifies validation by analysis and testing of specified safety\r\n        functions, achieved Category and achieved Performance Level.\r\n      <\/p>\r\n\r\n      <p>\r\n        The fault-evaluation tables used for detailed fault consideration\r\n        also remain in Part 2 rather than being reproduced fully in\r\n        ISO 13849-1:2023.\r\n      <\/p>\r\n\r\n      <p>\r\n        A revised Part 2 is under development. Until a replacement is\r\n        published and applicable, the current published status and the\r\n        relevant contents of ISO 13849-2:2012 should not simply be ignored.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         SISTEMA\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Where does SISTEMA fit?\r\n      <\/h3>\r\n\r\n      <p>\r\n        SISTEMA \u2014 the Safety Integrity Software Tool for the Evaluation of\r\n        Machine Applications \u2014 is provided by IFA to support engineering\r\n        work with ISO 13849.\r\n      <\/p>\r\n\r\n      <p>\r\n        It allows an engineer to represent safety functions and subsystems,\r\n        enter relevant safety-related data and calculate quantities used in\r\n        evaluating the attained Performance Level.\r\n      <\/p>\r\n\r\n\r\n      <div class=\"sistema-list\">\r\n\r\n        <div class=\"sistema-item\">\r\n\r\n          <strong>\r\n            SISTEMA can support the quantitative evaluation\r\n          <\/strong>\r\n\r\n          <p>\r\n            It can structure the model and work with parameters such as\r\n            PLr, Category, MTTF<sub>d<\/sub>, DC<sub>avg<\/sub>, CCF and\r\n            subsystem PFH data where appropriate.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"sistema-item\">\r\n\r\n          <strong>\r\n            SISTEMA does not determine the machinery risk automatically\r\n          <\/strong>\r\n\r\n          <p>\r\n            The engineer still needs to identify hazards, define the safety\r\n            function and establish the required PLr using the applicable\r\n            risk-assessment process and standards.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"sistema-item\">\r\n\r\n          <strong>\r\n            SISTEMA does not prove that the physical machine is correct\r\n          <\/strong>\r\n\r\n          <p>\r\n            Incorrect wiring, unsuitable software parameters, interface\r\n            errors, installation mistakes or incorrect input data can exist\r\n            even when the software model produces an acceptable PL result.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n\r\n        <div class=\"sistema-item\">\r\n\r\n          <strong>\r\n            SISTEMA does not replace validation\r\n          <\/strong>\r\n\r\n          <p>\r\n            The implemented safety function still needs the required\r\n            analysis, testing and documented validation against its Safety\r\n            Requirements Specification.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        A \u201cgreen\u201d calculation result is not a machine safety certificate.\r\n      <\/strong>\r\n\r\n      <p>\r\n        Calculation software can provide important engineering evidence,\r\n        but compliance depends on the complete safety lifecycle \u2014 including\r\n        correct specification, design, implementation, verification and\r\n        validation.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         DOCUMENTATION\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        Documentation connects the complete process\r\n      <\/h3>\r\n\r\n      <p>\r\n        Good functional-safety documentation should make it possible to\r\n        trace the engineering decisions from the original hazard and safety\r\n        function through to the final validation evidence.\r\n      <\/p>\r\n\r\n      <p>\r\n        A project record can therefore include:\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          the machinery risk assessment;\r\n        <\/li>\r\n\r\n        <li>\r\n          the Safety Requirements Specification;\r\n        <\/li>\r\n\r\n        <li>\r\n          the determined PLr;\r\n        <\/li>\r\n\r\n        <li>\r\n          subsystem architecture and safety-related data;\r\n        <\/li>\r\n\r\n        <li>\r\n          calculations and engineering assumptions;\r\n        <\/li>\r\n\r\n        <li>\r\n          software and configuration information where relevant;\r\n        <\/li>\r\n\r\n        <li>\r\n          verification records; and\r\n        <\/li>\r\n\r\n        <li>\r\n          validation plans, test results and conclusions.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n      <p>\r\n        This traceability becomes particularly important when a machine is\r\n        modified later, because engineers need to understand which original\r\n        assumptions and safety requirements may have been affected.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         PROCESS SUMMARY\r\n    ====================================================== -->\r\n\r\n    <div class=\"process-line\">\r\n      Specify \u2192 Design \u2192 Evaluate \u2192 Verify \u2192 Validate \u2192 Document\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         TAKEAWAY\r\n    ====================================================== -->\r\n\r\n    <div class=\"takeaway\">\r\n\r\n      <strong>\r\n        Key takeaway\r\n      <\/strong>\r\n\r\n      <p>\r\n        Verification checks whether the engineering design and evaluation\r\n        satisfy their defined requirements. Validation uses analysis and\r\n        testing to confirm that the implemented safety function fulfils its\r\n        Safety Requirements Specification. SISTEMA can support the\r\n        quantitative evaluation, but it does not replace either activity.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 10 \u2014 WHAT CHANGED IN ISO 13849-1:2023?\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s10,\r\n.iso13849-s10 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s10{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n  background:#f8fafb;\r\n\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s10 .inner{\r\n  max-width:880px;\r\n  margin:0 auto;\r\n  padding:78px 28px 84px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   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*\/\r\n\r\n.iso13849-s10 .revision-list{\r\n  max-width:800px;\r\n\r\n  margin:27px 0 0;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n\r\n  counter-reset:revisionItem;\r\n}\r\n\r\n.iso13849-s10 .revision-item{\r\n  position:relative;\r\n\r\n  padding:25px 0 26px 53px;\r\n\r\n  border-top:1px solid var(--line);\r\n\r\n  counter-increment:revisionItem;\r\n}\r\n\r\n.iso13849-s10 .revision-item:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s10 .revision-item::before{\r\n  content:counter(revisionItem, decimal-leading-zero);\r\n\r\n  position:absolute;\r\n\r\n  left:0;\r\n  top:27px;\r\n\r\n  color:#91a3ae;\r\n\r\n  font-size:10px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n}\r\n\r\n.iso13849-s10 .revision-item strong{\r\n  display:block;\r\n\r\n  margin-bottom:6px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n  line-height:1.55;\r\n}\r\n\r\n.iso13849-s10 .revision-item p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   EDITORIAL NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s10 .editorial-note{\r\n  max-width:800px;\r\n\r\n  margin-top:40px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s10 .editorial-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s10 .editorial-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s10 .editorial-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   VERSION NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s10 .version-note{\r\n  max-width:800px;\r\n\r\n  margin-top:40px;\r\n  padding:26px 29px;\r\n\r\n  background:#ffffff;\r\n}\r\n\r\n.iso13849-s10 .version-note .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s10 .version-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s10 .version-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s10 .version-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TAKEAWAY\r\n========================================================= *\/\r\n\r\n.iso13849-s10 .takeaway{\r\n  max-width:800px;\r\n\r\n  margin-top:47px;\r\n  padding-top:28px;\r\n\r\n  border-top:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s10 .takeaway strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:15px;\r\n}\r\n\r\n.iso13849-s10 .takeaway p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s10 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s10 .version-note{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s10\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      2023 Revision\r\n    <\/div>\r\n\r\n    <h2>\r\n      What Changed in ISO 13849-1:2023?\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      The fourth edition retains the familiar Performance Level framework,\r\n      but significantly updates how safety functions are specified,\r\n      structured, designed, evaluated and validated.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        ISO 13849-1:2023 should not be understood as a replacement for the\r\n        PL a-to-e concept. Performance Level, PLr, Category,\r\n        MTTF<sub>d<\/sub>, diagnostic coverage and common-cause failure\r\n        remain important parts of the methodology.\r\n      <\/p>\r\n\r\n      <p>\r\n        The larger change is in the surrounding engineering process.\r\n        The standard presents the safety function more clearly as a\r\n        combination of contributing subsystems and gives greater structure\r\n        to specification, software, validation and functional-safety\r\n        management.\r\n      <\/p>\r\n\r\n      <p>\r\n        For engineers familiar with ISO 13849-1:2015, the 2023 edition is\r\n        therefore an evolution and substantial modernisation of the\r\n        methodology rather than an entirely different system.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         SAFETY FUNCTION & SUBSYSTEMS\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        1. Stronger focus on the safety function and its subsystems\r\n      <\/h3>\r\n\r\n      <p>\r\n        One of the clearest structural changes is the stronger focus on\r\n        implementing a safety function as a combination of several\r\n        <strong>subsystems<\/strong>.\r\n      <\/p>\r\n\r\n      <p>\r\n        This makes the system-level view more explicit. Instead of treating\r\n        an individual safety device as though it were the complete safety\r\n        function, the engineer considers all of the subsystems that\r\n        contribute to the required safety behaviour.\r\n      <\/p>\r\n\r\n      <p>\r\n        Those subsystems can include self-developed structures as well as\r\n        previously evaluated subsystems with declared safety-related data.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         SRS\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        2. Safety-function specification and the SRS were strengthened\r\n      <\/h3>\r\n\r\n      <p>\r\n        Clause 5 gives greater attention to the specification of safety\r\n        functions and to the\r\n        <strong>Safety Requirements Specification (SRS)<\/strong>.\r\n      <\/p>\r\n\r\n      <p>\r\n        The intention is to establish clearly what the safety function must\r\n        do before the engineer attempts to prove that the design achieves\r\n        the required Performance Level.\r\n      <\/p>\r\n\r\n      <p>\r\n        Depending on the safety function, relevant requirements can include:\r\n      <\/p>\r\n\r\n\r\n      <ul class=\"plain-list\">\r\n\r\n        <li>\r\n          the required safety behaviour;\r\n        <\/li>\r\n\r\n        <li>\r\n          PLr;\r\n        <\/li>\r\n\r\n        <li>\r\n          relevant operating modes;\r\n        <\/li>\r\n\r\n        <li>\r\n          triggering conditions;\r\n        <\/li>\r\n\r\n        <li>\r\n          safe-state requirements;\r\n        <\/li>\r\n\r\n        <li>\r\n          response times;\r\n        <\/li>\r\n\r\n        <li>\r\n          fault-reaction behaviour;\r\n        <\/li>\r\n\r\n        <li>\r\n          reset and restart requirements; and\r\n        <\/li>\r\n\r\n        <li>\r\n          interfaces with other safety functions.\r\n        <\/li>\r\n\r\n      <\/ul>\r\n\r\n      <p>\r\n        Annex M provides supplementary information intended to support the\r\n        development of the Safety Requirements Specification.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         DESIGN \/ CATEGORY 2\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        3. Several subsystem design rules were clarified\r\n      <\/h3>\r\n\r\n      <p>\r\n        Clause 6 contains revised and clarified requirements for the design\r\n        of safety-related subsystems.\r\n      <\/p>\r\n\r\n      <p>\r\n        Among the changes is an optimised definition of\r\n        <strong>Category 2<\/strong>, together with clarification relating to\r\n        fault consideration, fault exclusion and the use of well-tried\r\n        components.\r\n      <\/p>\r\n\r\n      <p>\r\n        The revision reinforces a principle that applies throughout\r\n        ISO 13849: the Category identifies architectural and fault-behaviour\r\n        characteristics, but it does not independently determine the final\r\n        Performance Level.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         CCF\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        4. Common Cause Failure is considered more explicitly by subsystem\r\n      <\/h3>\r\n\r\n      <p>\r\n        Annex F expands and clarifies measures against\r\n        <strong>Common Cause Failure (CCF)<\/strong>.\r\n      <\/p>\r\n\r\n      <p>\r\n        An important practical change is the clearer expectation that\r\n        anti-CCF measures are considered at\r\n        <strong>subsystem level<\/strong>. Different subsystems can have\r\n        different technologies, layouts, environmental exposures and shared\r\n        failure mechanisms.\r\n      <\/p>\r\n\r\n      <p>\r\n        The engineer should therefore not assume that one generic CCF\r\n        assessment automatically represents every subsystem in a complex\r\n        safety function.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         SOFTWARE\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        5. Safety-related software requirements were revised and expanded\r\n      <\/h3>\r\n\r\n      <p>\r\n        Clause 7 contains improvements and clarifications relating to\r\n        safety-related software.\r\n      <\/p>\r\n\r\n      <p>\r\n        The 2023 edition addresses software as part of the complete\r\n        safety-related engineering process rather than treating hardware\r\n        reliability as sufficient by itself.\r\n      <\/p>\r\n\r\n      <p>\r\n        Annex N supplements those requirements with information on avoiding\r\n        systematic failures through software design and includes a simple\r\n        example relating to software validation.\r\n      <\/p>\r\n\r\n      <p>\r\n        This is particularly relevant because a system can satisfy its\r\n        random-hardware reliability targets and still fail to perform its\r\n        intended safety function because of specification, programming,\r\n        parameterisation or modification errors.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         VALIDATION\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        6. Validation requirements are now incorporated into Part 1\r\n      <\/h3>\r\n\r\n      <p>\r\n        ISO 13849-1:2023 introduces a dedicated validation Clause 10.\r\n        Normative validation requirements from ISO 13849-2 were revised\r\n        and incorporated into Part 1.\r\n      <\/p>\r\n\r\n      <p>\r\n        This brings validation more visibly into the same lifecycle as\r\n        specification, design and Performance Level evaluation.\r\n      <\/p>\r\n\r\n      <p>\r\n        It also reinforces the importance of the SRS: validation needs\r\n        defined requirements against which the implemented safety function\r\n        can be examined through analysis and testing.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        Incorporating validation requirements into Part 1 does not mean\r\n        ISO 13849-2:2012 automatically became irrelevant.\r\n      <\/strong>\r\n\r\n      <p>\r\n        ISO 13849-2:2012 remains a published standard at present, and its\r\n        fault-evaluation tables remain useful reference material. A revised\r\n        Part 2 is under development.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         PLr \/ PARAMETER P\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        7. Guidance for determining PLr \u2014 especially parameter P \u2014 changed\r\n      <\/h3>\r\n\r\n      <p>\r\n        Annex A retains the familiar S\u2013F\u2013P risk-graph principle but revises\r\n        the treatment of <strong>parameter P<\/strong>, the possibility of\r\n        avoiding the hazard or limiting the harm.\r\n      <\/p>\r\n\r\n      <p>\r\n        The 2023 edition provides more structured guidance so that the P1\r\n        or P2 decision reflects realistic operating conditions rather than\r\n        a simplistic question about whether an operator could theoretically\r\n        move away.\r\n      <\/p>\r\n\r\n      <p>\r\n        Factors can include operator characteristics, hazardous movement\r\n        speed, physical possibility of avoidance, recognition of the hazard\r\n        and operational complexity.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         FSM\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        8. Functional Safety Management received more explicit guidance\r\n      <\/h3>\r\n\r\n      <p>\r\n        Annex G.5 expands the guidance on\r\n        <strong>Functional Safety Management<\/strong>.\r\n      <\/p>\r\n\r\n      <p>\r\n        The objective is to provide a systematic approach to the design and\r\n        implementation of safety-related control systems and to reduce\r\n        errors introduced through specification, implementation and later\r\n        modification.\r\n      <\/p>\r\n\r\n      <p>\r\n        A functional safety plan can document relevant activities,\r\n        responsibilities, resources and procedures throughout the project\r\n        lifecycle. The appropriate form and depth depend on factors such as\r\n        the complexity, scale and novelty of the project.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         EMC\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        9. EMC immunity receives additional practical attention\r\n      <\/h3>\r\n\r\n      <p>\r\n        Annex L provides further information on achieving sufficiently high\r\n        electromagnetic immunity for safety-related control systems.\r\n      <\/p>\r\n\r\n      <p>\r\n        This matters because electromagnetic disturbance can become a\r\n        common or systematic influence on safety-related electronics,\r\n        interfaces and communication paths.\r\n      <\/p>\r\n\r\n      <p>\r\n        Functional safety therefore cannot be evaluated only through\r\n        reliability numbers while ignoring the real electromagnetic\r\n        environment in which the safety function must operate.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         ANNEXES\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        10. Several informative annexes provide additional engineering guidance\r\n      <\/h3>\r\n\r\n      <p>\r\n        The revised annexes make supporting engineering information more\r\n        explicit in several areas.\r\n      <\/p>\r\n\r\n\r\n      <ol class=\"revision-list\">\r\n\r\n        <li class=\"revision-item\">\r\n\r\n          <strong>\r\n            Annex F \u2014 Common Cause Failure\r\n          <\/strong>\r\n\r\n          <p>\r\n            Clarifies measures against CCF and their assessment at subsystem\r\n            level.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"revision-item\">\r\n\r\n          <strong>\r\n            Annex G.5 \u2014 Functional Safety Management\r\n          <\/strong>\r\n\r\n          <p>\r\n            Provides guidance for organising the functional-safety process\r\n            and documenting responsibilities and activities.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"revision-item\">\r\n\r\n          <strong>\r\n            Annex L \u2014 EMC\r\n          <\/strong>\r\n\r\n          <p>\r\n            Provides additional information intended to support adequate\r\n            electromagnetic immunity of safety-related control systems.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"revision-item\">\r\n\r\n          <strong>\r\n            Annex M \u2014 Safety Requirements Specification\r\n          <\/strong>\r\n\r\n          <p>\r\n            Provides supplementary information for defining and documenting\r\n            safety-function requirements.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"revision-item\">\r\n\r\n          <strong>\r\n            Annex N \u2014 Safety-Related Software\r\n          <\/strong>\r\n\r\n          <p>\r\n            Provides information relating to avoidance of systematic\r\n            software failures and includes a simple software-validation\r\n            example.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n\r\n        <li class=\"revision-item\">\r\n\r\n          <strong>\r\n            Annex O \u2014 Safety-Related Component Values\r\n          <\/strong>\r\n\r\n          <p>\r\n            Provides additional guidance for communicating and using\r\n            safety-related component data, aligned with the approach used\r\n            in VDMA 66413.\r\n          <\/p>\r\n\r\n        <\/li>\r\n\r\n      <\/ol>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         WHAT DID NOT CHANGE\r\n    ====================================================== -->\r\n\r\n    <div class=\"article-part\">\r\n\r\n      <h3>\r\n        What did not fundamentally change?\r\n      <\/h3>\r\n\r\n      <p>\r\n        The central idea remains familiar: define a safety function,\r\n        establish the required PLr, design the safety-related control\r\n        system, evaluate the achieved Performance Level, and verify and\r\n        validate that implementation.\r\n      <\/p>\r\n\r\n      <p>\r\n        Parameters such as Category, MTTF<sub>d<\/sub>,\r\n        DC<sub>avg<\/sub> and CCF continue to be important when evaluating\r\n        self-developed subsystems.\r\n      <\/p>\r\n\r\n      <p>\r\n        What changed most visibly is the structure around those calculations:\r\n        clearer safety-function specification, greater use of the subsystem\r\n        concept, stronger software and validation treatment, and more\r\n        explicit lifecycle and management guidance.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         ENGINEERING INTERPRETATION\r\n    ====================================================== -->\r\n\r\n    <aside class=\"editorial-note\">\r\n\r\n      <strong>\r\n        The 2023 edition places more emphasis on the engineering process,\r\n        not merely on obtaining a PL result.\r\n      <\/strong>\r\n\r\n      <p>\r\n        A well-supported safety claim should be traceable from the hazard\r\n        and Safety Requirements Specification through subsystem design,\r\n        reliability evaluation, software, CCF measures, verification and\r\n        validation.\r\n      <\/p>\r\n\r\n      <p>\r\n        The attained Performance Level remains essential, but it is one\r\n        result inside a broader functional-safety lifecycle.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <!-- =====================================================\r\n         CURRENT VERSION\r\n    ====================================================== -->\r\n\r\n    <div class=\"version-note\">\r\n\r\n      <span class=\"label\">\r\n        Current edition\r\n      <\/span>\r\n\r\n      <strong>\r\n        ISO 13849-1:2023 is the fourth edition of Part 1.\r\n      <\/strong>\r\n\r\n      <p>\r\n        It was published in April 2023 and replaced ISO 13849-1:2015 as the\r\n        current international edition.\r\n      <\/p>\r\n\r\n      <p>\r\n        The standard applies to safety-related parts of control systems for\r\n        high-demand and continuous modes, including their subsystems,\r\n        regardless of technology such as electrical, hydraulic, pneumatic\r\n        or mechanical.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         TAKEAWAY\r\n    ====================================================== -->\r\n\r\n    <div class=\"takeaway\">\r\n\r\n      <strong>\r\n        Key takeaway\r\n      <\/strong>\r\n\r\n      <p>\r\n        ISO 13849-1:2023 retains the Performance Level framework but makes\r\n        the complete functional-safety lifecycle more explicit. The biggest\r\n        practical changes are not simply new PL numbers; they concern how\r\n        safety functions are specified, divided into subsystems, designed,\r\n        managed, evaluated and validated.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 11 \u2014 COMMON MISUNDERSTANDINGS\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s11,\r\n.iso13849-s11 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s11{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s11 .inner{\r\n  max-width:880px;\r\n  margin:0 auto;\r\n  padding:78px 28px 84px;\r\n}\r\n\r\n\r\n\/* 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color:#465865;\r\n\r\n  font-size:18px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   INTRO\r\n========================================================= *\/\r\n\r\n.iso13849-s11 .copy{\r\n  max-width:800px;\r\n  margin-top:35px;\r\n}\r\n\r\n.iso13849-s11 .copy p{\r\n  margin:0 0 22px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.9;\r\n}\r\n\r\n.iso13849-s11 strong{\r\n  color:var(--navy);\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MISUNDERSTANDING LIST\r\n========================================================= *\/\r\n\r\n.iso13849-s11 .mis-list{\r\n  max-width:800px;\r\n\r\n  margin-top:48px;\r\n\r\n  counter-reset:misitem;\r\n}\r\n\r\n.iso13849-s11 .mis-item{\r\n  position:relative;\r\n\r\n  padding:38px 0 40px 57px;\r\n\r\n  border-top:1px solid var(--line);\r\n\r\n  counter-increment:misitem;\r\n}\r\n\r\n.iso13849-s11 .mis-item:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s11 .mis-item::before{\r\n  content:counter(misitem, decimal-leading-zero);\r\n\r\n  position:absolute;\r\n\r\n  left:0;\r\n  top:40px;\r\n\r\n  color:#91a3ae;\r\n\r\n  font-size:10px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n}\r\n\r\n.iso13849-s11 .mis-label{\r\n  display:block;\r\n\r\n  margin-bottom:7px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:10px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s11 .mis-item h3{\r\n  margin:0 0 14px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:21px;\r\n  line-height:1.4;\r\n  font-weight:820;\r\n\r\n  letter-spacing:-.01em;\r\n}\r\n\r\n.iso13849-s11 .mis-item p{\r\n  margin:0 0 17px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:15px;\r\n  line-height:1.85;\r\n}\r\n\r\n.iso13849-s11 .mis-item p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   CORRECTION\r\n========================================================= *\/\r\n\r\n.iso13849-s11 .correction{\r\n  margin-top:18px;\r\n  padding-left:20px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s11 .correction strong{\r\n  display:block;\r\n\r\n  margin-bottom:5px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:14px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s11 .correction p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   FINAL NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s11 .final-note{\r\n  max-width:800px;\r\n\r\n  margin-top:47px;\r\n  padding:27px 29px;\r\n\r\n  background:var(--soft);\r\n}\r\n\r\n.iso13849-s11 .final-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s11 .final-note p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s11 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s11 .mis-item{\r\n    padding-left:41px;\r\n  }\r\n\r\n  .iso13849-s11 .final-note{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s11\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Common Misunderstandings\r\n    <\/div>\r\n\r\n    <h2>\r\n      Common Mistakes When Interpreting ISO 13849\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      Many functional-safety errors begin when one parameter, one device\r\n      rating or one calculation result is treated as though it represented\r\n      the entire safety function.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        ISO 13849 is easier to apply when its concepts remain in the correct\r\n        order: define the safety function, determine PLr, design the\r\n        contributing subsystems, evaluate the achieved PL, and then verify\r\n        and validate the implemented function.\r\n      <\/p>\r\n\r\n      <p>\r\n        The misunderstandings below usually appear when one part of that\r\n        process is taken out of context.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"mis-list\">\r\n\r\n\r\n      <!-- 01 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cPL e is the highest level, so every safety function should use PL e.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          PL e is the highest level in the ISO 13849 Performance Level\r\n          scale, but functional-safety design is not based on selecting the\r\n          highest possible PL for every application.\r\n        <\/p>\r\n\r\n        <p>\r\n          The required level is <strong>PLr<\/strong>, established for a\r\n          defined safety function from risk assessment and applicable\r\n          machine-specific requirements.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            The design objective is for the achieved PL to satisfy the\r\n            required PLr. Higher performance can be used where appropriate,\r\n            but PL e should not be assigned automatically.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 02 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cCategory 4 automatically means PL e.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          Category 4 describes a demanding designated architecture and fault\r\n          behaviour, but Category alone does not establish the achieved\r\n          Performance Level.\r\n        <\/p>\r\n\r\n        <p>\r\n          Reliability, diagnostics, common-cause-failure measures and the\r\n          other applicable ISO 13849 requirements still need to support the\r\n          claimed result.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            Category 4 can support high Performance Levels, but\r\n            <strong>Category 4 is not another name for PL e<\/strong>.\r\n            Likewise, Category 3 should not simply be translated into PL d.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 03 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cIf one component is PL e, the complete safety function is PL e.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          A component or validated subsystem can have capability suitable\r\n          for use in a PL e safety function, but the complete function can\r\n          contain several contributing subsystems and interfaces.\r\n        <\/p>\r\n\r\n        <p>\r\n          Input sensing, logic, output control, wiring, software,\r\n          configuration and other relevant parts can all influence the\r\n          achieved Performance Level.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            Use the declared safety-related data of each applicable\r\n            subsystem, then evaluate the complete safety function.\r\n            The highest-rated component does not set the PL for everything\r\n            connected to it.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 04 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cType 4 means the safety function is PL e.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          IEC 61496 Type 4 describes the capability of electro-sensitive\r\n          protective equipment for use in applications\r\n          <strong>up to PL e \/ SIL 3<\/strong>.\r\n        <\/p>\r\n\r\n        <p>\r\n          It does not establish the Performance Level of the complete\r\n          machine safety function.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            Type 4 identifies ESPE capability. The achieved PL still depends\r\n            on the complete safety-related control function.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 05 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cPFH tells me how many years a machine will operate before an accident.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          PFH is the average frequency of dangerous failure per hour used in\r\n          functional-safety evaluation.\r\n        <\/p>\r\n\r\n        <p>\r\n          It is not a countdown to an accident and it is not equivalent to\r\n          mechanical service life, warranty life or expected replacement\r\n          interval.\r\n        <\/p>\r\n\r\n        <p>\r\n          ISO 13849-1:2023 defines PL e as\r\n          <strong>PFH &lt; 1 \u00d7 10<sup>\u22127<\/sup> per hour<\/strong>, but that\r\n          value remains a probabilistic functional-safety parameter rather\r\n          than a prediction of when an accident will occur.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            PFH helps quantify dangerous random failure of the\r\n            safety-related control function. It should not be converted\r\n            directly into an accident timetable.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 06 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cIf SISTEMA calculates PL d, the machine is certified PL d.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          SISTEMA is an engineering tool for modelling and evaluating\r\n          safety-related control functions according to ISO 13849.\r\n        <\/p>\r\n\r\n        <p>\r\n          The result depends on the structure, assumptions and safety-related\r\n          data entered into the model. The software does not inspect the\r\n          physical machine or certify the installation.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            A SISTEMA result can provide important engineering evidence,\r\n            but it does not replace risk assessment, correct implementation,\r\n            verification or validation.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 07 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cThe whole machine has one PLr.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          PLr belongs to a defined safety function. One machine can contain\r\n          several hazards and several safety functions, each requiring its\r\n          own consideration.\r\n        <\/p>\r\n\r\n        <p>\r\n          Access protection, prevention of unexpected restart, mode\r\n          selection, stopping functions and other safety functions can have\r\n          different requirements.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            Determine PLr function by function rather than assigning one\r\n            universal PLr number to the entire machine.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 08 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cPL d, SIL 2 and Category 3 are three equivalent labels.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          PL d and SIL 2 have a direct quantitative relationship because\r\n          both use the PFH interval from\r\n          1 \u00d7 10<sup>\u22127<\/sup> to less than\r\n          1 \u00d7 10<sup>\u22126<\/sup> per hour.\r\n        <\/p>\r\n\r\n        <p>\r\n          But ISO 13849 and IEC 62061 remain different functional-safety\r\n          methodologies. Category is different again: it describes an\r\n          ISO 13849 architecture and fault-behaviour concept.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            Compare PL and SIL through their quantitative safety-integrity\r\n            requirements where appropriate. Do not treat Category as a third\r\n            interchangeable conversion scale.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 09 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cOnce the PL calculation passes, validation is finished.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          A reliability calculation evaluates important quantitative and\r\n          architectural aspects of the safety-related control function.\r\n          It does not demonstrate that the real implementation behaves\r\n          correctly.\r\n        <\/p>\r\n\r\n        <p>\r\n          Wiring errors, incorrect parameters, software mistakes,\r\n          unsuitable reset behaviour or interface problems can exist even\r\n          when the calculation itself is correct.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            Calculation supports the safety argument. Validation uses\r\n            analysis and testing to confirm that the implemented safety\r\n            function fulfils its specified requirements.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- 10 -->\r\n\r\n      <article class=\"mis-item\">\r\n\r\n        <span class=\"mis-label\">\r\n          Misunderstanding\r\n        <\/span>\r\n\r\n        <h3>\r\n          \u201cBecause ISO 13849-1:2023 includes validation, ISO 13849-2 is obsolete.\u201d\r\n        <\/h3>\r\n\r\n        <p>\r\n          ISO 13849-1:2023 incorporated revised normative validation\r\n          requirements into Part 1, but that does not mean Part 2 simply\r\n          disappeared.\r\n        <\/p>\r\n\r\n        <p>\r\n          ISO 13849-2:2012 remains a published standard at present, and its\r\n          fault-evaluation tables continue to provide useful reference\r\n          material while a revised Part 2 is under development.\r\n        <\/p>\r\n\r\n        <div class=\"correction\">\r\n\r\n          <strong>\r\n            Better interpretation\r\n          <\/strong>\r\n\r\n          <p>\r\n            Read the 2023 Part 1 validation requirements together with the\r\n            current standards status and the relevant fault-evaluation\r\n            information in Part 2.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"final-note\">\r\n\r\n      <strong>\r\n        A useful test for oversimplification\r\n      <\/strong>\r\n\r\n      <p>\r\n        Be cautious whenever a functional-safety claim is reduced to one\r\n        device rating, one Category, one PL\/SIL conversion or one software\r\n        calculation. ISO 13849 evaluates a defined safety function through\r\n        the combined effects of specification, architecture, reliability,\r\n        diagnostics, fault behaviour, systematic measures, verification and\r\n        validation.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 12 \u2014 FAQ\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s12,\r\n.iso13849-s12 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s12{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n  background:#f8fafb;\r\n\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s12 .inner{\r\n  max-width:880px;\r\n  margin:0 auto;\r\n  padding:78px 28px 84px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   HEADER\r\n========================================================= *\/\r\n\r\n.iso13849-s12 .eyebrow{\r\n  display:flex;\r\n  align-items:center;\r\n  gap:10px;\r\n\r\n  margin-bottom:15px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:12px;\r\n  line-height:1.4;\r\n  font-weight:800;\r\n\r\n  letter-spacing:.1em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s12 .eyebrow::before{\r\n  content:\"12\";\r\n\r\n  color:var(--blue);\r\n\r\n  font-size:12px;\r\n  font-weight:900;\r\n}\r\n\r\n.iso13849-s12 .eyebrow::after{\r\n  content:\"\";\r\n\r\n  width:34px;\r\n  height:1px;\r\n\r\n  background:#9fd8f3;\r\n}\r\n\r\n.iso13849-s12 h2{\r\n  max-width:820px;\r\n\r\n  margin:0;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:clamp(31px,4vw,43px);\r\n  line-height:1.16;\r\n  font-weight:850;\r\n\r\n  letter-spacing:-.025em;\r\n}\r\n\r\n.iso13849-s12 .lead{\r\n  max-width:800px;\r\n\r\n  margin:22px 0 0;\r\n\r\n  color:#465865;\r\n\r\n  font-size:18px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   FAQ LIST\r\n========================================================= *\/\r\n\r\n.iso13849-s12 .faq-list{\r\n  max-width:800px;\r\n\r\n  margin-top:48px;\r\n\r\n  counter-reset:faqitem;\r\n}\r\n\r\n.iso13849-s12 .faq-item{\r\n  position:relative;\r\n\r\n  padding:36px 0 38px 55px;\r\n\r\n  border-top:1px solid var(--line);\r\n\r\n  counter-increment:faqitem;\r\n}\r\n\r\n.iso13849-s12 .faq-item:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s12 .faq-item::before{\r\n  content:counter(faqitem, decimal-leading-zero);\r\n\r\n  position:absolute;\r\n\r\n  left:0;\r\n  top:38px;\r\n\r\n  color:#91a3ae;\r\n\r\n  font-size:10px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n}\r\n\r\n.iso13849-s12 .faq-item h3{\r\n  margin:0 0 14px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:21px;\r\n  line-height:1.42;\r\n  font-weight:820;\r\n\r\n  letter-spacing:-.01em;\r\n}\r\n\r\n.iso13849-s12 .faq-item p{\r\n  margin:0 0 16px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:15px;\r\n  line-height:1.86;\r\n}\r\n\r\n.iso13849-s12 .faq-item p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n.iso13849-s12 strong{\r\n  color:var(--navy);\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   SMALL NOTE\r\n========================================================= *\/\r\n\r\n.iso13849-s12 .faq-note{\r\n  margin-top:18px;\r\n  padding-left:20px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s12 .faq-note p{\r\n  margin:0;\r\n\r\n  color:#526470;\r\n\r\n  font-size:14px;\r\n  line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   CLOSING\r\n========================================================= *\/\r\n\r\n.iso13849-s12 .closing{\r\n  max-width:800px;\r\n\r\n  margin-top:47px;\r\n  padding:27px 29px;\r\n\r\n  background:var(--soft);\r\n}\r\n\r\n.iso13849-s12 .closing strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s12 .closing p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s12 .inner{\r\n    padding:57px 20px 64px;\r\n  }\r\n\r\n  .iso13849-s12 .faq-item{\r\n    padding-left:40px;\r\n  }\r\n\r\n  .iso13849-s12 .closing{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section class=\"iso13849-s12\">\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Frequently Asked Questions\r\n    <\/div>\r\n\r\n    <h2>\r\n      ISO 13849 Performance Level FAQ\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      Concise answers to common questions about PL, PLr, Category,\r\n      MTTF<sub>d<\/sub>, DC<sub>avg<\/sub>, SIL, IEC 61496 Type\r\n      and SISTEMA.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"faq-list\">\r\n\r\n\r\n      <!-- FAQ 01 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          What does PL mean in ISO 13849?\r\n        <\/h3>\r\n\r\n        <p>\r\n          PL means <strong>Performance Level<\/strong>. ISO 13849-1 uses\r\n          five Performance Levels \u2014 PL a, PL b, PL c, PL d and PL e \u2014\r\n          to express the safety-related performance achieved by a defined\r\n          control-system safety function.\r\n        <\/p>\r\n\r\n        <p>\r\n          The achieved PL depends on the applicable architecture,\r\n          reliability, diagnostic capability, measures against\r\n          common-cause failures and other requirements of the standard.\r\n        <\/p>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 02 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          What is the difference between PL and PLr?\r\n        <\/h3>\r\n\r\n        <p>\r\n          <strong>PLr<\/strong> is the required Performance Level for a\r\n          defined safety function. It comes from the machinery risk\r\n          assessment together with applicable machine-specific\r\n          requirements and standards.\r\n        <\/p>\r\n\r\n        <p>\r\n          <strong>Achieved PL<\/strong> is the Performance Level demonstrated\r\n          by the designed and evaluated safety-related control function.\r\n        <\/p>\r\n\r\n        <div class=\"faq-note\">\r\n\r\n          <p>\r\n            The basic design objective is:\r\n            <strong>achieved PL \u2265 required PLr<\/strong>.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 03 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          Is PL e the highest Performance Level?\r\n        <\/h3>\r\n\r\n        <p>\r\n          Yes. PL e is the highest level in the ISO 13849 Performance\r\n          Level scale.\r\n        <\/p>\r\n\r\n        <p>\r\n          Under ISO 13849-1:2023, PL e is associated with\r\n          <strong>PFH below 1 \u00d7 10<sup>\u22127<\/sup> per hour<\/strong>.\r\n          However, that PFH condition does not by itself establish PL e;\r\n          the complete applicable requirements of ISO 13849 still need to\r\n          be fulfilled.\r\n        <\/p>\r\n\r\n        <p>\r\n          PL e should also not be selected automatically simply because a\r\n          machine appears dangerous. The required PLr must first be\r\n          established for the relevant safety function.\r\n        <\/p>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 04 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          Does Category 4 always achieve PL e?\r\n        <\/h3>\r\n\r\n        <p>\r\n          No. Category 4 describes architecture and fault behaviour, but\r\n          Category is only one part of Performance Level evaluation.\r\n        <\/p>\r\n\r\n        <p>\r\n          Reliability, diagnostic coverage, common-cause-failure measures\r\n          and the other applicable ISO 13849 requirements must also support\r\n          the result.\r\n        <\/p>\r\n\r\n        <p>\r\n          For the same reason, Category 3 should not automatically be\r\n          interpreted as PL d.\r\n        <\/p>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 05 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          Is PL d equivalent to SIL 2?\r\n        <\/h3>\r\n\r\n        <p>\r\n          PL d and SIL 2 have a particularly direct quantitative\r\n          relationship because both use the dangerous-failure PFH interval\r\n          from\r\n          <strong>1 \u00d7 10<sup>\u22127<\/sup> to less than\r\n          1 \u00d7 10<sup>\u22126<\/sup> per hour<\/strong>.\r\n        <\/p>\r\n\r\n        <p>\r\n          However, ISO 13849 and IEC 62061 remain different\r\n          functional-safety methodologies. Sharing a PFH range does not\r\n          make all of their design, architectural, software, verification\r\n          and validation requirements identical.\r\n        <\/p>\r\n\r\n        <div class=\"faq-note\">\r\n\r\n          <p>\r\n            It is better to speak of a\r\n            <strong>quantitative PFH correspondence<\/strong>\r\n            than to treat PL and SIL as universally interchangeable labels.\r\n          <\/p>\r\n\r\n        <\/div>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 06 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          What does MTTF<sub>d<\/sub> mean?\r\n        <\/h3>\r\n\r\n        <p>\r\n          MTTF<sub>d<\/sub> means\r\n          <strong>Mean Time To Dangerous Failure<\/strong>.\r\n          It is a statistical reliability parameter used in the evaluation\r\n          of dangerous random hardware failure.\r\n        <\/p>\r\n\r\n        <p>\r\n          It should not be interpreted as guaranteed service life or as a\r\n          statement that a component will physically operate for a certain\r\n          number of years before failing.\r\n        <\/p>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 07 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          What does DC<sub>avg<\/sub> mean?\r\n        <\/h3>\r\n\r\n        <p>\r\n          DC<sub>avg<\/sub> means\r\n          <strong>average Diagnostic Coverage<\/strong>.\r\n          It describes the effectiveness of diagnostics in detecting\r\n          dangerous failures in the relevant subsystem.\r\n        <\/p>\r\n\r\n        <p>\r\n          Diagnostic coverage contributes to the achieved safety\r\n          performance, but it must be considered together with architecture,\r\n          reliability and the other applicable ISO 13849 requirements.\r\n        <\/p>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 08 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          Does a Type 4 safety light curtain automatically make a safety function PL e?\r\n        <\/h3>\r\n\r\n        <p>\r\n          No. Under IEC 61496, Type 4 electro-sensitive protective equipment\r\n          has capability for use in applications\r\n          <strong>up to PL e \/ SIL 3<\/strong>.\r\n        <\/p>\r\n\r\n        <p>\r\n          That describes the capability of the protective equipment.\r\n          The complete safety function can also include logic, outputs,\r\n          interfaces, wiring, configuration and other safety-related\r\n          subsystems.\r\n        <\/p>\r\n\r\n        <p>\r\n          The achieved PL of that complete function therefore still needs\r\n          to be established separately.\r\n        <\/p>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 09 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          What does SISTEMA calculate?\r\n        <\/h3>\r\n\r\n        <p>\r\n          SISTEMA is an engineering tool provided by IFA to support the\r\n          evaluation of safety-related machine controls according to\r\n          ISO 13849.\r\n        <\/p>\r\n\r\n        <p>\r\n          It can model safety-related control structures and calculate\r\n          reliability values including the attained Performance Level.\r\n          Relevant inputs can include PLr, Category,\r\n          MTTF<sub>d<\/sub>, DC<sub>avg<\/sub>, CCF and other\r\n          safety-related data.\r\n        <\/p>\r\n\r\n        <p>\r\n          SISTEMA does not perform the machinery risk assessment, inspect\r\n          the physical installation or certify the machine.\r\n        <\/p>\r\n\r\n      <\/article>\r\n\r\n\r\n      <!-- FAQ 10 -->\r\n\r\n      <article class=\"faq-item\">\r\n\r\n        <h3>\r\n          Is ISO 13849-1:2023 the current edition, and is ISO 13849-2 still relevant?\r\n        <\/h3>\r\n\r\n        <p>\r\n          Yes. ISO 13849-1:2023 is the current fourth edition of\r\n          <em>Safety of machinery \u2014 Safety-related parts of control systems \u2014\r\n          Part 1: General principles for design<\/em>.\r\n        <\/p>\r\n\r\n        <p>\r\n          The 2023 edition incorporates revised normative validation\r\n          requirements into Part 1.\r\n        <\/p>\r\n\r\n        <p>\r\n          That does not mean ISO 13849-2:2012 simply became irrelevant.\r\n          Part 2 remains published at present, and its fault-evaluation\r\n          material can still be relevant while a revised edition is under\r\n          development.\r\n        <\/p>\r\n\r\n      <\/article>\r\n\r\n\r\n    <\/div>\r\n\r\n\r\n    <div class=\"closing\">\r\n\r\n      <strong>\r\n        Keep the concepts in the right order\r\n      <\/strong>\r\n\r\n      <p>\r\n        Hazard and risk assessment \u2192 define the safety function \u2192\r\n        determine PLr \u2192 design and evaluate the contributing subsystems \u2192\r\n        establish the achieved PL \u2192 verify and validate the implementation.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n\n\n\n<style>\r\n\/* =========================================================\r\n   ISO 13849 BLOG V2\r\n   SECTION 13 \u2014 REFERENCES & SOURCES\r\n   Final Editorial \/ Technical Blog Style\r\n========================================================= *\/\r\n\r\n.iso13849-s13,\r\n.iso13849-s13 *{\r\n  box-sizing:border-box;\r\n}\r\n\r\n.iso13849-s13{\r\n  --text:#1d2933;\r\n  --body:#364854;\r\n  --navy:#102331;\r\n  --blue:#129fe9;\r\n  --blue-dark:#0878b5;\r\n  --line:#dfe5e9;\r\n  --soft:#f7f9fa;\r\n\r\n  width:100%;\r\n  background:#f8fafb;\r\n\r\n  color:var(--text);\r\n  font-family:inherit;\r\n}\r\n\r\n.iso13849-s13 .inner{\r\n  max-width:880px;\r\n  margin:0 auto;\r\n  padding:78px 28px 88px;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   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line-height:1.8;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   INTRO\r\n========================================================= *\/\r\n\r\n.iso13849-s13 .copy{\r\n  max-width:800px;\r\n  margin-top:35px;\r\n}\r\n\r\n.iso13849-s13 .copy p{\r\n  margin:0 0 22px;\r\n\r\n  color:var(--body);\r\n\r\n  font-size:16px;\r\n  line-height:1.9;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   REFERENCES\r\n========================================================= *\/\r\n\r\n.iso13849-s13 .references{\r\n  max-width:800px;\r\n\r\n  margin:45px 0 0;\r\n  padding:0;\r\n\r\n  list-style:none;\r\n\r\n  counter-reset:reference;\r\n}\r\n\r\n.iso13849-s13 .reference{\r\n  position:relative;\r\n\r\n  padding:29px 0 30px 55px;\r\n\r\n  border-top:1px solid var(--line);\r\n\r\n  counter-increment:reference;\r\n}\r\n\r\n.iso13849-s13 .reference:last-child{\r\n  border-bottom:1px solid var(--line);\r\n}\r\n\r\n.iso13849-s13 .reference::before{\r\n  content:counter(reference, decimal-leading-zero);\r\n\r\n  position:absolute;\r\n\r\n  left:0;\r\n  top:31px;\r\n\r\n  color:#91a3ae;\r\n\r\n  font-size:10px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n}\r\n\r\n.iso13849-s13 .reference-org{\r\n  display:block;\r\n\r\n  margin-bottom:6px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:10px;\r\n  line-height:1.5;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.07em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s13 .reference-title{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.58;\r\n  font-weight:800;\r\n}\r\n\r\n.iso13849-s13 .reference p{\r\n  margin:0 0 10px;\r\n\r\n  color:#536571;\r\n\r\n  font-size:13px;\r\n  line-height:1.78;\r\n}\r\n\r\n.iso13849-s13 .reference p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n.iso13849-s13 .reference a{\r\n  display:inline;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:13px;\r\n  line-height:1.65;\r\n  font-weight:750;\r\n\r\n  text-decoration:none;\r\n\r\n  border-bottom:1px solid rgba(8,120,181,.28);\r\n}\r\n\r\n.iso13849-s13 .reference a:hover{\r\n  border-bottom-color:var(--blue-dark);\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   STANDARDS STATUS\r\n========================================================= *\/\r\n\r\n.iso13849-s13 .status-note{\r\n  max-width:800px;\r\n\r\n  margin-top:44px;\r\n  padding:27px 29px;\r\n\r\n  background:#ffffff;\r\n}\r\n\r\n.iso13849-s13 .status-note .label{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--blue-dark);\r\n\r\n  font-size:11px;\r\n  line-height:1.4;\r\n  font-weight:850;\r\n\r\n  letter-spacing:.09em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n.iso13849-s13 .status-note strong{\r\n  display:block;\r\n\r\n  margin-bottom:9px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s13 .status-note p{\r\n  margin:0 0 13px;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n.iso13849-s13 .status-note p:last-child{\r\n  margin-bottom:0;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   TECHNICAL DISCLAIMER\r\n========================================================= *\/\r\n\r\n.iso13849-s13 .disclaimer{\r\n  max-width:800px;\r\n\r\n  margin-top:40px;\r\n  padding:3px 0 3px 24px;\r\n\r\n  border-left:3px solid var(--blue);\r\n}\r\n\r\n.iso13849-s13 .disclaimer strong{\r\n  display:block;\r\n\r\n  margin-bottom:8px;\r\n\r\n  color:var(--navy);\r\n\r\n  font-size:16px;\r\n  line-height:1.5;\r\n}\r\n\r\n.iso13849-s13 .disclaimer p{\r\n  margin:0;\r\n\r\n  color:#536571;\r\n\r\n  font-size:14px;\r\n  line-height:1.82;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   REVIEW DATE\r\n========================================================= *\/\r\n\r\n.iso13849-s13 .review-date{\r\n  max-width:800px;\r\n\r\n  margin-top:35px;\r\n\r\n  color:#82919a;\r\n\r\n  font-size:11px;\r\n  line-height:1.7;\r\n}\r\n\r\n\r\n\/* =========================================================\r\n   MOBILE\r\n========================================================= *\/\r\n\r\n@media (max-width:700px){\r\n\r\n  .iso13849-s13 .inner{\r\n    padding:57px 20px 68px;\r\n  }\r\n\r\n  .iso13849-s13 .reference{\r\n    padding-left:40px;\r\n  }\r\n\r\n  .iso13849-s13 .status-note{\r\n    padding:23px 21px;\r\n  }\r\n\r\n}\r\n<\/style>\r\n\r\n\r\n<section\r\n  id=\"references-sources\"\r\n  class=\"iso13849-s13\"\r\n>\r\n\r\n  <div class=\"inner\">\r\n\r\n    <div class=\"eyebrow\">\r\n      Primary References\r\n    <\/div>\r\n\r\n    <h2>\r\n      References &amp; Sources\r\n    <\/h2>\r\n\r\n    <p class=\"lead\">\r\n      This guide is based primarily on current ISO and IEC standards\r\n      information and practical resources published by IFA \/ DGUV.\r\n    <\/p>\r\n\r\n\r\n    <div class=\"copy\">\r\n\r\n      <p>\r\n        The summaries in this article are intended to help explain the\r\n        relationship between Performance Level, PLr, subsystem design,\r\n        PFH, Category, SIL, ESPE Type, verification and validation.\r\n      <\/p>\r\n\r\n      <p>\r\n        For machinery design, conformity assessment or formal\r\n        functional-safety work, the applicable standards and\r\n        machine-specific requirements should always be consulted directly.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <ol class=\"references\">\r\n\r\n\r\n      <!-- 01 -->\r\n\r\n      <li class=\"reference\">\r\n\r\n        <span class=\"reference-org\">\r\n          International Organization for Standardization\r\n        <\/span>\r\n\r\n        <span class=\"reference-title\">\r\n          ISO 13849-1:2023 \u2014 Safety of machinery \u2014\r\n          Safety-related parts of control systems \u2014\r\n          Part 1: General principles for design\r\n        <\/span>\r\n\r\n        <p>\r\n          Current fourth edition of ISO 13849-1. It specifies methodology\r\n          and requirements for the design and integration of safety-related\r\n          parts of control systems performing safety functions, including\r\n          their subsystems and safety-related software.\r\n        <\/p>\r\n\r\n        <a href=\"https:\/\/www.iso.org\/standard\/73481.html\" target=\"_blank\" rel=\"noopener noreferrer\">\r\n          Official ISO publication \u2192\r\n        <\/a>\r\n\r\n      <\/li>\r\n\r\n\r\n      <!-- 02 -->\r\n\r\n      <li class=\"reference\">\r\n\r\n        <span class=\"reference-org\">\r\n          International Organization for Standardization\r\n        <\/span>\r\n\r\n        <span class=\"reference-title\">\r\n          ISO 13849-2:2012 \u2014 Safety of machinery \u2014\r\n          Safety-related parts of control systems \u2014\r\n          Part 2: Validation\r\n        <\/span>\r\n\r\n        <p>\r\n          Current published edition of Part 2. It addresses validation by\r\n          analysis and testing of specified safety functions, achieved\r\n          Category and achieved Performance Level.\r\n        <\/p>\r\n\r\n        <p>\r\n          ISO currently indicates that a revised Part 2 is under development.\r\n        <\/p>\r\n\r\n        <a href=\"https:\/\/www.iso.org\/standard\/53640.html\" target=\"_blank\" rel=\"noopener noreferrer\">\r\n          Official ISO publication \u2192\r\n        <\/a>\r\n\r\n      <\/li>\r\n\r\n\r\n      <!-- 03 -->\r\n\r\n      <li class=\"reference\">\r\n\r\n        <span class=\"reference-org\">\r\n          International Electrotechnical Commission\r\n        <\/span>\r\n\r\n        <span class=\"reference-title\">\r\n          IEC 62061:2021 + AMD1:2024 + AMD2:2026 \u2014\r\n          Safety of machinery \u2014 Functional safety of\r\n          safety-related control systems\r\n        <\/span>\r\n\r\n        <p>\r\n          Current consolidated IEC publication for machinery\r\n          functional-safety control systems. It addresses the design,\r\n          integration, verification and validation of safety-related\r\n          control systems and uses Safety Integrity Levels.\r\n        <\/p>\r\n\r\n        <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/112847\" target=\"_blank\" rel=\"noopener noreferrer\">\r\n          Official IEC publication \u2192\r\n        <\/a>\r\n\r\n      <\/li>\r\n\r\n\r\n      <!-- 04 -->\r\n\r\n      <li class=\"reference\">\r\n\r\n        <span class=\"reference-org\">\r\n          International Electrotechnical Commission\r\n        <\/span>\r\n\r\n        <span class=\"reference-title\">\r\n          IEC 61496-1:2020 \u2014 Safety of machinery \u2014\r\n          Electro-sensitive protective equipment \u2014\r\n          Part 1: General requirements and tests\r\n        <\/span>\r\n\r\n        <p>\r\n          Fourth edition of the general IEC 61496 standard for\r\n          electro-sensitive protective equipment. It specifies general\r\n          design, construction and testing requirements for non-contact\r\n          ESPE used as part of safety-related systems.\r\n        <\/p>\r\n\r\n        <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/63115\" target=\"_blank\" rel=\"noopener noreferrer\">\r\n          Official IEC publication \u2192\r\n        <\/a>\r\n\r\n      <\/li>\r\n\r\n\r\n      <!-- 05 -->\r\n\r\n      <li class=\"reference\">\r\n\r\n        <span class=\"reference-org\">\r\n          International Electrotechnical Commission\r\n        <\/span>\r\n\r\n        <span class=\"reference-title\">\r\n          IEC 61496-2:2020 \u2014 Safety of machinery \u2014\r\n          Electro-sensitive protective equipment \u2014\r\n          Part 2: Particular requirements for equipment using\r\n          active opto-electronic protective devices (AOPDs)\r\n        <\/span>\r\n\r\n        <p>\r\n          Particular requirements for AOPD-based ESPE, including the\r\n          sensing technology commonly used in safety light curtains and\r\n          related optical protective equipment.\r\n        <\/p>\r\n\r\n        <p>\r\n          The standard concerns the ESPE and its interface with the machine;\r\n          it does not prescribe the detection-zone dimensions or safeguarding\r\n          position for every individual machine application.\r\n        <\/p>\r\n\r\n        <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/63117\" target=\"_blank\" rel=\"noopener noreferrer\">\r\n          Official IEC publication \u2192\r\n        <\/a>\r\n\r\n      <\/li>\r\n\r\n\r\n      <!-- 06 -->\r\n\r\n      <li class=\"reference\">\r\n\r\n        <span class=\"reference-org\">\r\n          IFA \/ German Social Accident Insurance\r\n        <\/span>\r\n\r\n        <span class=\"reference-title\">\r\n          SISTEMA \u2014 Safety Integrity Software Tool for the Evaluation\r\n          of Machine Applications\r\n        <\/span>\r\n\r\n        <p>\r\n          IFA software and supporting resources for evaluating\r\n          safety-related machine controls in the context of ISO 13849-1.\r\n          SISTEMA supports modelling designated architectures and calculating\r\n          reliability values including the attained Performance Level.\r\n        <\/p>\r\n\r\n        <a href=\"https:\/\/www.dguv.de\/ifa\/praxishilfen\/practical-solutions-machine-safety\/software-sistema\/index.jsp\" target=\"_blank\" rel=\"noopener noreferrer\">\r\n          Official IFA SISTEMA resources \u2192\r\n        <\/a>\r\n\r\n      <\/li>\r\n\r\n\r\n      <!-- 07 -->\r\n\r\n      <li class=\"reference\">\r\n\r\n        <span class=\"reference-org\">\r\n          IFA \/ German Social Accident Insurance\r\n        <\/span>\r\n\r\n        <span class=\"reference-title\">\r\n          Performance Level Calculator \u2014\r\n          Practical illustration of EN ISO 13849 relationships\r\n        <\/span>\r\n\r\n        <p>\r\n          IFA practical resource illustrating how Category,\r\n          MTTF<sub>d<\/sub>, diagnostic coverage, PFH and Performance Level\r\n          relate within the designated-architecture methodology.\r\n        <\/p>\r\n\r\n        <a href=\"https:\/\/www.dguv.de\/ifa\/praxishilfen\/practical-solutions-machine-safety\/performance-level-calculator\/index.jsp\" target=\"_blank\" rel=\"noopener noreferrer\">\r\n          Official IFA Performance Level resources \u2192\r\n        <\/a>\r\n\r\n      <\/li>\r\n\r\n\r\n      <!-- 08 -->\r\n\r\n      <li class=\"reference\">\r\n\r\n        <span class=\"reference-org\">\r\n          IFA \/ German Social Accident Insurance\r\n        <\/span>\r\n\r\n        <span class=\"reference-title\">\r\n          Safety of machine controls to EN ISO 13849 \u2014\r\n          IFA practical resources\r\n        <\/span>\r\n\r\n        <p>\r\n          IFA technical resources covering risk evaluation,\r\n          safety-related control design, verification, SISTEMA and\r\n          practical application of EN ISO 13849.\r\n        <\/p>\r\n\r\n        <a href=\"https:\/\/www.dguv.de\/ifa\/praxishilfen\/practical-solutions-machine-safety\/sicherheit-von-maschinensteuerungen\/index.jsp\" target=\"_blank\" rel=\"noopener noreferrer\">\r\n          View IFA practical resources \u2192\r\n        <\/a>\r\n\r\n      <\/li>\r\n\r\n\r\n    <\/ol>\r\n\r\n\r\n    <!-- =====================================================\r\n         CURRENT STATUS\r\n    ====================================================== -->\r\n\r\n    <div class=\"status-note\">\r\n\r\n      <span class=\"label\">\r\n        Standards status\r\n      <\/span>\r\n\r\n      <strong>\r\n        Standards and publication status reviewed in 2026.\r\n      <\/strong>\r\n\r\n      <p>\r\n        ISO 13849-1:2023 remains the current fourth edition of Part 1.\r\n        ISO 13849-2:2012 remains the current published Part 2 while a\r\n        revised edition is under development.\r\n      <\/p>\r\n\r\n      <p>\r\n        IEC 62061 is currently available as the consolidated publication\r\n        IEC 62061:2021 + AMD1:2024 + AMD2:2026.\r\n      <\/p>\r\n\r\n      <p>\r\n        IEC 61496-1:2020 and IEC 61496-2:2020 remain the current fourth\r\n        editions of their respective publications.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n\r\n    <!-- =====================================================\r\n         DISCLAIMER\r\n    ====================================================== -->\r\n\r\n    <aside class=\"disclaimer\">\r\n\r\n      <strong>\r\n        Technical note\r\n      <\/strong>\r\n\r\n      <p>\r\n        This article is an educational overview and does not reproduce all\r\n        requirements, tables, definitions or conditions contained in the\r\n        referenced standards. It does not replace the applicable standards,\r\n        a machine-specific risk assessment, professional engineering\r\n        judgement, verification, validation or conformity-assessment\r\n        obligations.\r\n      <\/p>\r\n\r\n    <\/aside>\r\n\r\n\r\n    <div class=\"review-date\">\r\n      Technical references and standards status last reviewed: 2026.\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n<\/section>\n","protected":false},"excerpt":{"rendered":"<p>Machine Safety \u00b7 Functional Safety ISO 13849 Performance Level (PL a\u2013e): A Practical Guide to Machine Safety A practical introduction to Performance Level, PLr, PFH, Category, MTTFd, DCavg, CCF and the engineering process used to evaluate safety-related control functions under ISO 13849-1. When a machinery risk-reduction measure depends on a control system, the safety-related parts [&hellip;]<\/p>\n","protected":false},"author":6,"featured_media":2860,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_gspb_post_css":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-2851","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-qjkh-blogs"],"blocksy_meta":{"has_hero_section":"disabled","disable_header":"no","content_style_source":"inherit","styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":8}},"_links":{"self":[{"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/posts\/2851","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/comments?post=2851"}],"version-history":[{"count":0,"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/posts\/2851\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/media\/2860"}],"wp:attachment":[{"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/media?parent=2851"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/categories?post=2851"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/industrialsafetysensor.com\/es\/wp-json\/wp\/v2\/tags?post=2851"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}