EN ISO 13849-1:2023

Safety of machinery - Safety-related parts of control systems - Part 1: General principles for design (ISO 13849-1:2023)

This document specifies a methodology and provides related requirements, recommendations and guidance for the design and integration of safety‐related parts of control systems (SRP/CS) that perform safety functions, including the design of software.
This document applies to SRP/CS for high demand and continuous modes of operation including their subsystems, regardless of the type of technology and energy (e.g. electrical, hydraulic, pneumatic, and mechanical). This document does not apply to low demand mode of operation.
NOTE 1        See 3.1.44 and the IEC 61508 series for low demand mode of operation.
This document does not specify the safety functions or required performance levels (PLr) that are to be used in particular applications.
NOTE 2        This document specifies a methodology for SRP/CS design without considering if certain machinery (e.g. mobile machinery) has specific requirements. These specific requirements can be considered in a Type‑C standard.
This document does not give specific requirements for the design of products/components that are parts of SRP/CS. Specific requirements for the design of some components of SRP/CS are covered by applicable ISO and IEC standards.
This document does not provide specific measures for security aspects (e.g. physical, IT-security, cyber security).
NOTE 3        Security issues can have an effect on safety functions. See ISO/TR 22100-4 and IEC/TR 63074 for further information.

Sicherheit von Maschinen - Sicherheitsbezogene Teile von Steuerungen - Teil 1: Allgemeine Gestaltungsleitsätze (ISO 13849-1:2023)

Dieses Dokument legt ein Verfahren fest und enthält zugehörige Anforderungen, Empfehlungen und einen Leitfaden für die Gestaltung und Integration sicherheitsbezogener Teile von Steuerungen (SRP/CS), die Sicherheitsfunktionen ausführen, einschließlich des Entwurfs von Software.
Dieses Dokument ist anwendbar für SRP/CS in der Betriebsart mit hoher Anforderungsrate und der Betriebsart mit kontinuierlicher Anforderung einschließlich ihrer Teilsysteme, ungeachtet der Art der Technologie und der Energie (z. B. elektrisch, hydraulisch, pneumatisch und mechanisch). Dieses Dokument ist nicht anwendbar für Betriebsarten mit niedriger Anforderungsrate.
ANMERKUNG 1   Siehe 3.1.44 und die Normenreihe IEC 61508 für die Betriebsart mit niedriger Anforderungsrate.
Dieses Dokument legt nicht fest, welche Sicherheitsfunktionen oder welche erforderlichen Performance Level (PLr) für spezielle Fälle zu verwenden sind.
ANMERKUNG 2   Dieses Dokument legt ein Verfahren für die Gestaltung von SRP/CS fest, ohne dabei zu berücksichtigen, ob für bestimmte Maschinen (z. B. ortsveränderliche Maschinen) spezifische Anforderungen gelten. Diese spezifischen Anforderungen können in einer Typ-C-Norm festgelegt sein.
Dieses Dokument stellt keine speziellen Anforderungen an den Entwurf von Produkten/Bauteilen, die Teile von SRP/CS sind. Spezifische Anforderungen an den Entwurf einiger Bauteile eines SRP/CS werden in den zutreffenden ISO- und IEC-Normen behandelt.
Dieses Dokument enthält keine spezifischen Maßnahmen für weitere Sicherheitsaspekte (z. B. physische Sicherheit, IT-Sicherheit, Cybersicherheit).
ANMERKUNG 3   Securityaspekte können einen Einfluss auf Sicherheitsfunktionen haben. Siehe ISO/TR 22100-4 und IEC/TR 63074 für weitere Informationen.

Sécurité des machines - Parties des systèmes de commande relatives à la sécurité - Partie 1: Principes généraux de conception (ISO 13849-1:2023)

Le présent document spécifie une méthodologie et fournit des exigences, des recommandations et des conseils portant sur la conception et l'intégration des parties des systèmes de commande relatives à la sécurité (SRP/CS) qui réalisent des fonctions de sécurité, incluant la conception de logiciels.
Le présent document s'applique aux SRP/CS pour les modes de fonctionnement à forte sollicitation et continu, incluant leurs sous-systèmes, indépendamment du type de technologie et d'énergie utilisé (par exemple, électrique, hydraulique, pneumatique et mécanique). Le présent document ne s'applique pas au mode de fonctionnement à faible sollicitation.
NOTE 1        Voir 3.1.44 et la série IEC 61508 pour le mode de fonctionnement à faible sollicitation.
Le présent document ne spécifie pas les fonctions de sécurité et les niveaux de performance requis (PLr) qui doivent être utilisés dans un cas particulier.
NOTE 2        Le présent document spécifie une méthodologie pour la conception des SRP/CS sans tenir compte d'exigences spécifiques pour certaines machines (par exemple, machines mobiles). Ces exigences spécifiques peuvent être prises en compte dans une norme de type‑C.
Le présent document ne donne pas d'exigences spécifiques pour la conception de produits/composants intégrés dans les SRP/CS. Les exigences spécifiques pour la conception de certains composants de SRP/CS sont couvertes par les normes ISO et IEC applicables.
Le présent document ne fournit pas de mesures spécifiques pour les aspects de sécurité (par exemple, physique, sécurité informatique (IT-security), cybersécurité).
NOTE 3        Les problèmes de sécurité peuvent avoir un effet sur les fonctions de sécurité. Voir l'ISO/TR 22100-4 et l'IEC/TR 63074 pour d'autres informations.

Varnost strojev - Z varnostjo povezani deli krmilnih sistemov - 1. del: Splošna načela za načrtovanje (ISO 13849-1:2023)

Ta dokument določa metodologijo in zagotavlja povezane zahteve, priporočila in smernice za načrtovanje in integracijo z varnostjo povezanih delov krmilnih sistemov (SRP/CS), ki izvajajo varnostne funkcije, vključno z načrtovanjem programske opreme.
Ta dokument se uporablja za z varnostjo povezane dele krmilnih sistemov, ki delujejo v načinu delovanja z visokimi zahtevami in v neprekinjenem načinu, vključno z njihovimi podsistemi, ne glede na vrsto uporabljene tehnologije in energije (npr. električne, hidravlične, pnevmatske in mehanske). Ta dokument se ne uporablja za način delovanja z nizkimi zahtevami.
OPOMBA 1: Za način delovanja z nizkimi zahtevami glej točko 3.1.44 in skupino standardov IEC 61508.
Ta dokument ne določa varnostnih funkcij ali zahtevanih ravni učinkovitosti (PLr), ki jih je treba uporabiti v posameznem primeru.
OPOMBA 2: Ta dokument določa metodologijo za načrtovanje z varnostjo povezanih delov krmilnih sistemov brez upoštevanja, ali imajo določeni stroji (npr. mobilni stroji) posebne zahteve. Te posebne zahteve je mogoče upoštevati v standardu tipa C.
Ta dokument ne podaja posebnih zahtev za načrtovanje izdelkov/komponent, ki so del z varnostjo povezanih delov krmilnih sistemov. Posebne zahteve za načrtovanje nekaterih komponent z varnostjo povezanih delov krmilnih sistemov so zajete v standardih ISO in IEC.
Ta dokument ne določa posebnih ukrepov za varnostne vidike (npr. fizična varnost, IT-varnost, računalniška varnost).
OPOMBA 3: Varnostne težave lahko vplivajo na varnostne funkcije. Za dodatne informacije glej ISO/TR 22100-4 in IEC/TR 63074.

General Information

• Status: Published
• Publication Date: 16-May-2023
• ICS: 13.110 - Safety of machinery
• Technical Committee: CEN/TC 114 - Safety of machinery
• Drafting Committee: CEN/TC 114 - Safety of machinery
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 17-May-2023
• Completion Date: 17-May-2023
• Directive: 2006/42/EC - Directive 2006/42/EC of the European Parliament and of the Council of 17 May 2006 on machinery, and amending Directive 95/16/EC (recast)
• Mandate: M/396 - Mandate to CEN and Cenelec for standardisation in the field of machinery
• Ref Project: SIST EN ISO 13849-1:2023 - Safety of machinery - Safety-related parts of control systems - Part 1: General principles for design (ISO 13849-1:2023)

Relations

• Replaces: EN ISO 13849-1:2015 - Safety of machinery - Safety-related parts of control systems - Part 1: General principles for design (ISO 13849-1:2015)
• Effective Date: 18-Jan-2023

Overview

EN ISO 13849-1:2023 (identical to ISO 13849-1:2023) - "Safety of machinery - Safety‑related parts of control systems - Part 1: General principles for design" - defines a systematic methodology, requirements, recommendations and guidance for the design and integration of safety‑related parts of control systems (SRP/CS) that implement safety functions. The standard applies to SRP/CS in high‑demand and continuous modes of operation, across technologies and energy types (electrical, hydraulic, pneumatic, mechanical). It does not apply to low‑demand mode (see IEC 61508 series) and does not prescribe specific safety functions or mandated performance levels for particular machines.

Key Topics and Technical Requirements

• Safety requirements specification (SRS): identification, description and documentation of safety functions and their requirements.
• Determination of required performance level (PLr): process for deriving the performance level required for each safety function from risk assessment and risk reduction measures.
• Design and evaluation of SRP/CS architectures: categories and architectures, and how they relate to reliability parameters.
• Reliability metrics and analyses:
  • Mean Time to Dangerous Failure (MTTFD) for components and channels
  • Diagnostic coverage (DC) and its influence on achievable PL
  • Common cause failures (CCF) and measures to mitigate them
  • Systematic failure control and requirements for well‑tried components
• Combination of subsystems: methods to combine subsystem characteristics to achieve an overall PL for a safety function.
• Software safety: principles for software design, verification and restrictions on parameterization, including requirements for tools used for manual software parameterization.
• Documentation, review and validation: SRS review, verification and link to validation guidance (ISO 13849‑2).

Notes: The standard excludes detailed product/component design rules and specific cyber/IT security measures (security can affect safety; see ISO/TR 22100‑4, IEC/TR 63074).

Practical Applications and Who Uses It

• Primary users: machine designers, safety engineers, control system engineers, integrators, machine builders, notified bodies and conformity assessors.
• Typical applications:
  • Designing SRP/CS for industrial machinery (presses, conveyors, robotic cells, material‑handling systems) across electrical and fluid power systems.
  • Preparing SRS, selecting architectures and components to meet required PLs derived from risk assessments.
  • Establishing software safety practices and parameterization controls.
  • Demonstrating conformity with the EU Machinery Directive where applicable (Annex ZA relationship).

Related Standards

• ISO 13849-2 (Validation)
• ISO 12100 (Risk assessment and reduction)
• IEC 61508-3 (Software requirements for functional safety)
• IEC 62061 (Functional safety of safety‑related control systems)
• ISO 20607, IEC/IEEE 82079-1 (instructions and information for use)
• ISO/TR 22100-4, IEC/TR 63074 (security considerations affecting safety)

Keywords: EN ISO 13849-1:2023, ISO 13849-1, safety of machinery, SRP/CS, performance level, PL, safety requirements specification, machine safety.

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2023
Varnost strojev - Z varnostjo povezani deli krmilnih sistemov - 1. del: Splošna
načela za načrtovanje (ISO 13849-1:2023)
Safety of machinery - Safety-related parts of control systems - Part 1: General principles
for design (ISO 13849-1:2023)
Sicherheit von Maschinen - Sicherheitsbezogene Teile von Steuerungen - Teil 1:
Allgemeine Gestaltungsleitsätze (ISO 13849-1:2023)
Sécurité des machines - Parties des systèmes de commande relatives à la sécurité -
Partie 1 : Principes généraux de conception (ISO 13849-1:2023)
Ta slovenski standard je istoveten z: EN ISO 13849-1:2023
ICS:
13.110 Varnost strojev Safety of machinery
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 13849-1
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2023
EUROPÄISCHE NORM
ICS 13.110 Supersedes EN ISO 13849-1:2015
English Version
Safety of machinery - Safety-related parts of control
systems - Part 1: General principles for design (ISO 13849-
1:2023)
Sécurité des machines - Parties des systèmes de Sicherheit von Maschinen - Sicherheitsbezogene Teile
commande relatives à la sécurité - Partie 1: Principes von Steuerungen - Teil 1: Allgemeine
généraux de conception (ISO 13849-1:2023) Gestaltungsleitsätze (ISO 13849-1:2023)
This European Standard was approved by CEN on 3 March 2023.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13849-1:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of EU Directive 2006/42/EC aimed to be covered . 4
European foreword
This document (EN ISO 13849-1:2023) has been prepared by Technical Committee ISO/TC 199 "Safety
of machinery" in collaboration with Technical Committee CEN/TC 114 “Safety of machinery” the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by November 2023, and conflicting national standards
shall be withdrawn at the latest by May 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 13849-1:2015.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association, and supports essential requirements of EU
Directive(s) / Regulation(s).
For the relationship with EU Directive(s) / Regulation(s), see informative Annex ZA, which is an integral
part of this document.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 13849-1:2023 has been approved by CEN as EN ISO 13849-1:2023 without any
modification.
Annex ZA
(informative)
Relationship between this European Standard and the essential
requirements of EU Directive 2006/42/EC aimed to be covered
This European Standard has been prepared under a Commission’s standardization request M/396
Mandate to CEN and CENELEC for Standardisation in the field of machinery" to provide one voluntary
means of conforming to essential requirements of Directive 2006/42/EC of the European Parliament
and of the Council of 17 May 2006 on machinery, and amending Directive 95/16/EC (recast).
Once this standard is cited in the Official Journal of the European Union under that Directive,
compliance with the normative clauses of this standard given in Table ZA.1 confers, within the limits of
the scope of this standard, a presumption of conformity with the corresponding essential requirements
of that Directive, and associated EFTA regulations.
Table ZA.1 — Correspondence between this European Standard and Directive 2006/42/EC
The relevant essential Clause(s)/subclause(s) Remarks/Notes
Requirements of Directive of this EN
2006/42/EC
1.1.6 9
1.2.1 6, 7, 10
1.2.3 5.2.2.4 This subclause only deals with
the restart function
1.2.4.1 5.2.2.2 This subclause only deals with
those safety-related stop function
achieving stop category 0 or 1.
1.2.4.2 5.2.2.2 This subclause only deals with
those safety-related stop function
achieving stop category 2.
1.2.4.3 5.2.1 This subclause only deals with
the safety requirements
specification (SRS) of an
emergency stop function
1.2.5 5.2.2.9
1.2.6 5.2.1.3 item i), 5.2.2.8
1.6.1 11
1.6.2 11
1.6.4 11
1.7.4.2 (e, g, i, r, s) 13 This subclause only deals with
the instruction for safety
functions.
Table ZA.2 — Applicable Standards to confer presumption of conformity as described in this
Annex ZA
Reference in International Title Corresponding European
Clause 2 Standard Edition Standard Edition
ISO 12100:2010 ISO 12100:2010 Safety of machinery — General EN ISO 12100:2010
principles for design — Risk
assessment and risk reduction
ISO 13849-2:2012 ISO 13849-2:2012 Safety of machinery — Safety- EN ISO 13849-2:2012
related parts of control systems —
Part 2: Validation
ISO 13855:2010 ISO 13855:2010 Safety of machinery — Positioning EN ISO 13855:2010
of safeguards with respect to the
approach of the human body
ISO 20607:2019 ISO 20607:2019 Safety of machinery — Instruction EN ISO 20607:2019
handbook — General drafting
principles
IEC 61508-3:2010 IEC 61508-3:2010 Functional safety of IEC 61508-3:2010
electrical/electronic/programmabl
e electronic safety-related systems
— Part 3: Software requirements
IEC 62046:2018 IEC 62046:2018 Safety of machinery — Application EN IEC 62046:2018
of protective equipment to detect
the presence of persons
IEC 62061:2021 IEC 62061:2021 Safety of machinery — Functional EN IEC 62061:2021
safety of safety-related control
systems
IEC/IEEE 82079- IEC/IEEE 82079- Preparation of information for use EN IEC/IEEE 82079-1:2019
1:2019 1:2019 (instructions for use) of products —
Part 1: Principles and general
requirements
The documents listed in the Column 1 of Table ZA.2, in whole or in part, are normatively referenced in this
document, i.e. are indispensable for its application. The achievement of the presumption of conformity is
subject to the application of the edition of Standards as listed in Column 4 or, if no European Standard
Edition exists, the International Standard Edition given in Column 2 of Table ZA.2.
WARNING 1 — Presumption of conformity stays valid only as long as a reference to this European Standard
is maintained in the list published in the Official Journal of the European Union. Users of this standard
should consult frequently the latest list published in the Official Journal of the European Union.
WARNING 2 — Other Union legislation may be applicable to the product(s) falling within the scope of this
standard.
INTERNATIONAL ISO
STANDARD 13849-1
Fourth edition
2023-04
Safety of machinery — Safety-related
parts of control systems —
Part 1:
General principles for design
Sécurité des machines — Parties des systèmes de commande relatives
à la sécurité —
Partie 1: Principes généraux de conception
Reference number
ISO 13849-1:2023(E)
ISO 13849-1:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 13849-1:2023(E)
Contents Page
Foreword . vi
Introduction .viii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Symbols and abbreviated terms . 10
4 Overview .12
4.1 Risk assessment and risk reduction process at the machine .12
4.2 Contribution to the risk reduction . 14
4.3 Design process of an SRP/CS . 14
4.4 Methodology . 15
4.5 Required information . 16
4.6 Safety function realization by using subsystems . 17
5 Specification of safety functions .17
5.1 Identification and general description of the safety function . 17
5.2 Safety requirements specification . 18
5.2.1 General requirements . 18
5.2.2 Requirements for specific safety functions . 21
5.2.3 Minimizing motivation to defeat safety functions . 24
5.2.4 Remote access . 25
5.3 Determination of required performance level (PL ) for each safety function . .25
r
5.4 Review of the safety requirements specification (SRS) . 26
5.5 Decomposition of SRP/CS into subsystems . 26
6 Design considerations .27
6.1 Evaluation of the achieved performance level . 27
6.1.1 General overview of performance level . 27
6.1.2 Correlation between performance level (PL) and safety integrity level (SIL) .29
6.1.3 Architecture — Categories and their relation to MTTF of each channel,
D
average diagnostic coverage and common cause failure (CCF).29
6.1.4 Mean time to dangerous failure (MTTF ) .36
D
6.1.5 Diagnostic coverage (DC) . 37
6.1.6 Common cause failures (CCFs) .38
6.1.7 Systematic failures .38
6.1.8 Simplified procedure for estimating the performance level for subsystems .39
6.1.9 Alternative procedure to determine the performance level and PFH
without MTTF .40
D
6.1.10 Fault consideration and fault exclusion . 42
6.1.11 Well-tried component . 43
6.2 Combination of subsystems to achieve an overall performance level of the safety
function . 43
6.2.1 General . 43
6.2.2 Known PFH values . 43
6.2.3 Unknown PFH values .44
6.3 Software based manual parameterization . .44
6.3.1 General .44
6.3.2 Influences on safety-related parameters . 45
6.3.3 Requirements for software based manual parameterization .46
6.3.4 Verification of the parameterization tool . 47
6.3.5 Documentation of software based manual parameterization . 47
7 Software safety requirements .47
7.1 General . 47
iii
ISO 13849-1:2023(E)
7.2 Limited variability language (LVL) and full variability language (FVL) .49
7.2.1 Limited variability language (LVL) .49
7.2.2 Full variability language (FVL) .49
7.2.3 Decision for limited variability language (LVL) or full variability language
(FVL) .49
7.3 Safety-related embedded software (SRESW) . 51
7.3.1 Design of safety-related embedded software (SRESW) . 51
7.3.2 Alternative procedures for non-accessible embedded software . 52
7.4 Safety-related application software (SRASW) . 52
8 Verification of the achieved performance level .55
9 Ergonomic aspects of design .55
10 Validation . .55
10.1 Validation principles. 55
10.1.1 General . 55
10.1.2 Validation plan . 57
10.1.3 Generic fault lists .58
10.1.4 Specific fault lists .58
10.1.5 Information for validation .58
10.2 Validation of the safety requirements specification (SRS) . 59
10.3 Validation by analysis.60
10.3.1 General .60
10.3.2 Analysis techniques .60
10.4 Validation by testing .60
10.4.1 General .60
10.4.2 Measurement accuracy . 61
10.4.3 Additional requirements for testing . 62
10.4.4 Number of test samples . 62
10.4.5 Testing methods . . 62
10.5 Validation of the safety functions .63
10.6 Validation of the safety integrity of the SRP/CS .63
10.6.1 Validation of subsystem(s).63
10.6.2 Validation of measures against systematic failures .64
10.6.3 Validation of safety-related software .65
10.6.4 Validation of combination of subsystems.66
10.6.5 Overall validation of safety integrity .66
10.7 Validation of environmental requirements .66
10.8 Validation record . 67
10.9 Validation maintenance requirements . 67
11 Maintainability of SRP/CS .67
12 Technical documentation .68
13 Information for use .68
13.1 General .68
13.2 Information for SRP/CS integration.68
13.3 Information for user . 69
Annex A (informative) Guidance for the determination of required performance level (PL ) .71
r
Annex B (informative) Block method and safety-related block diagram .76
Annex C (informative) Calculating or evaluating MTTF values for single components .78
D
Annex D (informative) Simplified method for estimating MTTF for each channel .86
D
Annex E (informative) Estimates for diagnostic coverage (DC) for functions and subsystems .88
Annex F (informative) Method for quantification of measures against common cause
failures (CCF) .92
Annex G (informative) Systematic failure .96
iv
ISO 13849-1:2023(E)
Annex H (informative) Example of a combination of several subsystems . 100
Annex I (informative) Examples for the simplified procedure to estimate the PL of
subsystems . 103
Annex J (informative) Example of SRESW realisation . 111
Annex K (informative) Numerical representation of Figure 12 . 115
Annex L (informative) Electromagnetic interference (EMI) immunity . 120
Annex M (informative) Additional information for safety requirements specification (SRS) .124
Annex N (informative) Avoiding systematic failure in software design . 126
Annex O (informative) Safety-related values of components or parts of control systems . 146
Bibliography . 149
v
ISO 13849-1:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 199, Safety of machinery, in collaboration
with the European Committee for Standardization (CEN) Technical Committee CEN/TC 114, Safety of
machinery, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna
Agreement).
This fourth edition cancels and replaces the third edition (ISO 13849-1:2015), which has been
technically revised.
The main changes are as follows:
— the whole document was reorganized to better follow the design and development process for
control systems;
— new Clause 4 on recommendation for risk assessment;
— specification of the safety functions (updated Clause 5);
— combination of several subsystems (updated in Clause 6);
— new Clause 7 on software safety requirements;
— new Clause 9 on ergonomic aspects of design;
— validation (updated Clause 8 and moved to Clause 10);
— new G.5 on management of the functional safety;
— new Annex L on electromagnetic interference (EMI) immunity;
— new Annex M with additional information for safety requirements specification;
— new Annex N on fault-avoiding measures for the design of safety related software;
— new Annex O with safety-related values of components or parts of the control systems.
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ISO 13849-1:2023(E)
A list of all parts in the ISO 13849 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO 13849-1:2023(E)
Introduction
The structure of safety standards in the field of machinery is as follows:
a) Type-A standards (basis standards) give basic concepts, principles for design and general aspects
that can be applied to machinery.
b) Type-B standards (generic safety standards) deal with one or more safety aspect(s), or one or more
type(s) of safeguards that can be used across a wide range of machinery:
— type-B1 standards on particular safety aspects (e.g. safety distances, surface temperature,
noise);
— type-B2 standards on safeguards (e.g. two-hand controls, interlocking devices, pressure
sensitive devices, guards).
c) Type-C standards (machinery safety standards) deal with detailed safety requirements for a
particular machine or group of machines.
This document is a type-B1 standard as defined in ISO 12100:2010.
The first edition of this document was published in 1999 based on EN 954-1:1996 (withdrawn standard).
The second edition was revised in 2006 and the third edition was revised in 2015.
This document is of relevance, in particular for the following stakeholder groups with regard to
machinery safety:
— machine manufacturers (small, medium and large enterprises);
— health and safety bodies (regulators, accident prevention organisations, market surveillance).
Others can be affected by the level of machinery safety achieved with the means of the document:
— machine users/employers (small, medium and large enterprises);
— machine users/employees (e.g. trade unions);
— service providers, e.g. for maintenance (small, medium and large enterprises);
— consumers (i.e. machinery intended for use by consumers).
The above-mentioned stakeholder groups have been given the possibility to participate in the drafting
process of this document.
In addition, this document is intended for standardization bodies elaborating type-C standards, as
defined in ISO 12100:2010.
The requirements of this document can be supplemented or modified by a type-C standard.
For machines which are covered by the scope of a type-C standard and which have been designed and
built according to the requirements of that standard, the requirements of that type-C standard take
precedence.
NOTE 1 The examples and basis for most content is based on stationary machines in factory applications.
However, other machines are not excluded. This document was written without considering if certain machinery
(e.g. mobile machinery) has specific requirements. However, this document is intended to be used across many
machinery industries and as a basis for type-C standards developers, as far as applicable.
This document is intended to give guidance to those involved in the design and assessment of control
systems, and those preparing type-B2 or type-C standards.
Risk reduction according to ISO 12100:2010, Clause 6, is accomplished by applying, in the following
sequence, inherently safe design measures, safeguarding and/or complementary risk reduction
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ISO 13849-1:2023(E)
measures and information for use. A designer can reduce risks by risk reduction measures that can
have safety functions. Parts of machinery control systems that are assigned to provide safety functions
are called safety-related parts of control systems (SRP/CS). These can consist of hardware or a
combination of hardware and software and can either be separate from the machine control system
or an integral part of it. In addition to implementing safety functions, SRP/CS can also implement
operational functions.
ISO 12100:2010 is used for risk assessment of the machine. Annex A of this document can be used for
the determination of the required performance level (PL ) of a safety function performed by the SRP/
r
CS, where its PL is not specified in the applicable type-C standard. This document is relevant for the
r
SRP/CS safety functions that are used to address risks for cases where a risk assessment conducted
according to ISO 12100:2010 determines that a risk reduction measure is needed that relies on a safety
function (e.g. interlocking guard). In those cases, the safety-related control system performs a safety
function. This document is intended to be used to design and evaluate the SRP/CS. Only the part of the
control system that is safety-related falls under the scope of this document.
Figure 1 illustrates the relationship between ISO 12100:2010 and this document. For a detailed
overview see Figure 2.
NOTE 2 See also ISO/TR 22100-2:2013 for further information.
NOTE Based on ISO/TR 22100-2:2013, Figure 2.
Figure 1 — Integration of this document (ISO 13849-1) within the risk reduction process of
ISO 12100:2010
NOTE 3 Figure 1 shows where the SRP/CS contributes to the risk reduction process of ISO 12100:2010: Step
2. The SRP/CS supports the combined risk reduction measures by the implementation of safety functions. The
ability of safety-related parts of control systems to perform a safety function under foreseeable conditions is
allocated one of five levels, called performance levels (PL). The required performance level (PL ) for a particular
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safety function (depending on the required risk reduction) will be determined by risk estimation.
Informative Annex A of this document contains a method for risk estimation and can be used for the
determination of the PL of a safety function performed by the SRP/CS. Any risk estimation method will
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show a variance because of the subjective nature of the evaluation criteria. In comparison to Annex A,
type-C standards can have more specific risk estimation methods for specific machine applications.
The frequency of dangerous failure of the safety function depends on several factors, including but
not limited to, hardware and software structure, the extent of fault detection mechanisms [diagnostic
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ISO 13849-1:2023(E)
coverage (DC)], reliability of components [mean time to dangerous failure (MTTF ), common cause
D
failure (CCF)], design process, operating stress, environmental conditions and operation procedures.
In order to facilitate the design of SRP/CS and the assessment of achieved PL, this document employs
a methodology based on the categorization of architectures with specific design criteria (e.g. MTTF ,
D
DC ) and specified behaviour under fault conditions. These architectures are allocated one of five
avg
levels termed Categories B, 1, 2, 3 and 4.
Functional safety considers the failure characteristics of elements/components performing a safety
function. For each safety function, this failure characteristic is expressed as the frequency of dangerous
failure per hour (PFH).
The performance levels and categories can be applied to SRP/CS, e.g.:
— control units (e.g. a logic unit for control functions, data processing, monitoring);
— electro-sensitive protective devices (e.g. photoelectric barriers), pressure sensitive devices.
The performance levels can be defined, and categories determined, for subsystems of SRP/CS using
safety parts (components), e.g.:
— protective devices (e.g. two-hand control devices, interlocking devices);
— power control elements (e.g. relays, valves);
— sensors and HMI elements (e.g. position sensors, enable switches).
Machinery covered by this document can range from simple (e.g. small kitchen machines, or automatic
doors and gates) to complex (e.g. packaging machines, printing machines, presses and integrated
machinery into a system).
This document and IEC 62061 both specify a methodology and provide related guidance for the design
and implementation of safety-related control systems of machinery.
The requirements of Clause 10 of this document supersede the requirements of ISO 13849-2:2012
(excluding the informative annexes).
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INTERNATIONAL STANDARD ISO 13849-1:2023(E)
Safety of machinery — Safety-related parts of control
systems —
Part 1:
General principles for design
1 Scope
This document specifies a methodology and provides related requirements, recommendations and
guidance for the design and integration of safety-related parts of control systems (SRP/CS) that perform
safety functions, including the design of software.
This document applies to SRP/CS for high demand and continuous modes of operation including their
subsystems, regardless of the type of technology and energy (e.g. electrical, hydraulic, pneumatic, and
mechanical). This document does not apply to low demand mode of operation.
NOTE 1 See 3.1.44 and the IEC 61508 series for low demand mode of operation.
This document does not specify the safety functions or required performance levels (PL ) that are to be
r
used in particular applications.
NOTE 2 This document specifies a methodology for SRP/CS design without considering if certain machinery
(e.g. mobile machinery) has specific requirements. These specific requirements can be considered in a Type-C
standard.
This document does not give specific requirements for the design of products/components that are
parts of SRP/CS. Specific requirements for the design of some components of SRP/CS are covered by
applicable ISO and IEC standards.
This document does not provide specific measures for security aspects (e.g. physical, IT-security, cyber
security).
NOTE 3 Security issues can have an effect on safety functions. See ISO/TR 22100-4 and IEC/TR 63074 for
further information.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction
ISO 13849-2:2012, Safety of machinery — Safety-related parts of control systems — Part 2: Validation
ISO 13855:2010, Safety of machinery — Positioning of safeguards with respect to the approach speeds of
parts of the human body
ISO 20607:2019, Safety of machinery — Instruction handbook — General drafting principles
IEC 61508-3:2010, Functional safety of electrical/electronic/programmable electronic safety-related
systems — Part 3: Software requirements
IEC 62046:2018, Safety of machinery — Application of protective equipment to detect the presence of
persons
ISO 13849-1:2023(E)
IEC 62061:2021, Safety of machinery — Functional safety of safety-related control systems
IEC/IEEE 82079-1:2019, Preparation of information for use (instructions for use) of products — Part 1:
Principles and general requirements
3 Terms, definitions, symbols a
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