IEC TS 61508-3-1:2016

IEC TS 61508-3-1 ®
Edition 1.0 2016-07
TECHNICAL
SPECIFICATION
Functional safety of electrical/electronic/programmable electronic safety-related
systems –
Part 3-1: Software requirements – Reuse of pre-existing software elements to
implement all or part of a safety function
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IEC TS 61508-3-1 ®
Edition 1.0 2016-07
TECHNICAL
SPECIFICATION
Functional safety of electrical/electronic/programmable electronic safety-related

systems –
Part 3-1: Software requirements – Reuse of pre-existing software elements to

implement all or part of a safety function

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.240.50 ISBN 978-2-8322-3516-4

– 2 – IEC TS 61508-3-1:2016 © IEC 2016
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative References . 6
3 Terms and definitions . 6
4 Requirements . 6
Bibliography . 10

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FUNCTIONAL SAFETY OF ELECTRICAL/ELECTRONIC/PROGRAMMABLE
ELECTRONIC SAFETY-RELATED SYSTEMS –

Part 3-1: Software requirements –
Reuse of pre-existing software elements
to implement all or part of a safety function

FOREWORD
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Technical specifications are subject to review within three years of publication to decide
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– 4 – IEC TS 61508-3-1:2016 © IEC 2016
IEC TS 61508-3-1, which is a technical specification, has been prepared by subcommittee
65A: System aspects, of IEC technical committee 65: Industrial-process measurement, control
and automation.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
65A/780/DTS 65A/802/RVC
Full information on the voting for the approval of this technical specification 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 in 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 website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

INTRODUCTION
The requirements set out in this technical specification deal with the reuse of software
elements when they are intended to form part of a safety function.
In many fields of automation, software elements are used today in support of safety functions.
Such applications will certainly be further developed and extended. Software engineers,
however, do not always wish to write the software for these applications from scratch, but will
in many cases use already existing software and integrate it with the new application which
might be slightly different from the one for which the software was originally specified.
In IEC 61508-3:2010, a requirement is given in 7.4.2.12. It offers three routes to the
achievement of the necessary integrity for the pre-existing software element. The
requirements to compl
...