IEC 61508-7:2010

IEC 61508-7 ®
Edition 2.0 2010-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Functional safety of electrical/electronic/programmable electronic safety-related
systems –
Part 7: Overview of techniques and measures

Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité –
Partie 7: Présentation de techniques et mesures

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IEC 61508-7 ®
Edition 2.0 2010-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Functional safety of electrical/electronic/programmable electronic safety-related
systems –
Part 7: Overview of techniques and measures

Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité –
Partie 7: Présentation de techniques et mesures

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XG
CODE PRIX
ICS 25.040.40; 35.240.50 ISBN 978-2-88910-530-4
– 2 – 61508-7 © IEC:2010
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.7
2 Normative references .9
3 Definitions and abbreviations.9
Annex A (informative) Overview of techniques and measures for E/E/PE safety-related
systems: control of random hardware failures (see IEC 61508-2).10
Annex B (informative) Overview of techniques and measures for E/E/PE safety related
systems: avoidance of systematic failures (see IEC 61508-2 and IEC 61508-3) .27
Annex C (informative) Overview of techniques and measures for achieving software
safety integrity (see IEC 61508-3).54
Annex D (informative) A probabilistic approach to determining software safety integrity
for pre-developed software .107
Annex E (informative) Overview of techniques and measures for design of ASICs . 112
Annex F (informative) Definitions of properties of software lifecycle phases. 126
Annex G (informative) Guidance for the development of safety-related object oriented
software.132
Bibliography.134
Index .137

Figure 1 – Overall framework of IEC 61508.8

Table C.1 – Recommendations for specific programming languages .86
Table D.1 – Necessary history for confidence to safety integrity levels . 107
Table D.2 – Probabilities of failure for low demand mode of operation . 108
Table D.3 – Mean distances of two test points .109
Table D.4 – Probabilities of failure for high demand or continuous mode of operation .110
Table D.5 – Probability of testing all program properties .111
Table F.1 – Software Safety Requirements Specification . 126
Table F.2 – Software design and development: software architecture design . 127
Table F.3 – Software design and development: support tools and programming
language.128
Table F.4 – Software design and development: detailed design . 128
Table F.5 – Software design and development: software module testing and integration. 129
Table F.6 – Programmable electronics integration (hardware and software). 129
Table F.7 – Software aspects of system safety validation .130
Table F.8 – Software modification.130
Table F.9 – Software verification.131
Table F.10 – Functional safety assessment .131
Table G.1 – Object Oriented Software Architecture . 132
Table G.2 – Object Oriented Detailed Design.133
Table G.3 – Some Oriented Detailed terms .133

61508-7 © IEC:2010 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FUNCTIONAL SAFETY OF ELECTRICAL/ELECTRONIC/
PROGRAMMABLE ELECTRONIC SAFETY-RELATED SYSTEMS –

Part 7: Overview of techniques and measures

FOREWORD
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61508-7 has been prepared by subcommittee 65A: System
aspects, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This second edition cancels and replaces the first edition published in 2000. This edition
constitutes a technical revision.
This edition has been subject to a thorough review and incorporates many comments received
at the various revision stages.

– 4 – 61508-7 © IEC:2010
The text of this standard is based on the following documents:
FDIS Report on voting
65A/554/FDIS 65A/578/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61508 series, published under the general title Functional safety
of electrical / electronic / programmable electronic safety-related systems, can be found on
the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site
...