IEC 61508-2:2010

IEC 61508-2 ®
Edition 2.0 2010-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Functional safety of electrical/electronic/programmable electronic safety-related
systems –
Part 2: Requirements for electrical/electronic/programmable electronic safety-
related systems
Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité –
Partie 2: Exigences pour les systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité

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IEC 61508-2 ®
Edition 2.0 2010-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Functional safety of electrical/electronic/programmable electronic safety-related
systems –
Part 2: Requirements for electrical/electronic/programmable electronic safety-
related systems
Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité –
Partie 2: Exigences pour les systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XD
CODE PRIX
ICS 25.040.40 ISBN 978-2-88910-525-0
– 2 – 61508-2 © IEC:2010
CONTENTS
FOREWORD.5
INTRODUCTION.7
1 Scope.9
2 Normative references .12
3 Definitions and abbreviations.12
4 Conformance to this standard.12
5 Documentation .13
6 Management of functional safety .13
7 E/E/PE system safety lifecycle requirements .13
7.1 General .13
7.1.1 Objectives and requirements – general.13
7.1.2 Objectives .13
7.1.3 Requirements .13
7.2 E/E/PE system design requirements specification .17
7.2.1 Objective .17
7.2.2 General .17
7.2.3 E/E/PE system design requirements specification.18
7.3 E/E/PE system safety validation planning .19
7.3.1 Objective .19
7.3.2 Requirements .19
7.4 E/E/PE system design and development.19
7.4.1 Objective .20
7.4.2 General requirements .20
7.4.3 Synthesis of elements to achieve the required systematic capability.22
7.4.4 Hardware safety integrity architectural constraints.23
7.4.5 Requirements for quantifying the effect of random hardware failures .32
7.4.6 Requirements for the avoidance of systematic faults .34
7.4.7 Requirements for the control of systematic faults.35
7.4.8 Requirements for system behaviour on detection of a fault .35
7.4.9 Requirements for E/E/PE system implementation .36
7.4.10 Requirements for proven in use elements .38
7.4.11 Additional requirements for data communications .39
7.5 E/E/PE system integration.40
7.5.1 Objective .40
7.5.2 Requirements .40
7.6 E/E/PE system operation and maintenance procedures .41
7.6.1 Objective .41
7.6.2 Requirements .41
7.7 E/E/PE system safety validation .42
7.7.1 Objective .42
7.7.2 Requirements .42
7.8 E/E/PE system modification.43
7.8.1 Objective .43
7.8.2 Requirements .43
7.9 E/E/PE system verification .44
7.9.1 Objective .44

61508-2 © IEC:2010 – 3 –
7.9.2 Requirements .44
8 Functional safety assessment.46
Annex A (normative) Techniques and measures for E/E/PE safety-related systems –
control of failures during operation.47
Annex B (normative) Techniques and measures for E/E/PE safety-related systems –
avoidance of systematic failures during the different phases of the lifecycle .62
Annex C (normative) Diagnostic coverage and safe failure fraction.71
Annex D (normative) Safety manual for compliant items .74
Annex E (normative) Special architecture requirements for integrated circuits (ICs)
with on-chip redundancy .76
Annex F (informative) Techniques and measures for ASICs – avoidance of systematic
failures .81
Bibliography.89

Figure 1 – Overall framework of the IEC 61508 series .11
Figure 2 – E/E/PE system safety lifecycle (in realisation phase).14
Figure 3 – ASIC development lifecycle (the V-Model).15
Figure 4 – Relationship between and scope of IEC 61508-2 and IEC 61508-3 .15
Figure 5 – Determination of the maximum SIL for specified architecture (E/E/PE safety-
related subsystem comprising a number of series elements, see 7.4.4.2.3) .28
Figure 6 – Determination of the maximum SIL for specified architecture (E/E/PE safety-
related subsystem comprised of two subsystems X & Y, see 7.4.4.2.4).30
Figure 7 – Architectures for data communication.40

Table 1 – Overview – realisation phase of the E/E/PE system safety lifecycle.16
Table 2 – Maximum allowable safety integrity level for a safety function carried out by
a type A safety-related element or subsystem.26
Table 3 – Maximum allowable safety integrity level for a safety function carried out by
a type B safety-related element or subsystem.27
Table A.1 – Faults or failures to be assumed when quantifying the effect of random
hardware failures or to be taken into account in the derivation of safe failure fraction .49
Table A.2 – Electrical components .51
Table A.3 – Electronic components.51
Table A.4 – Processing units .52
Table A.5 – Invariable memory ranges.52
Table A.6 – Variable memory ranges .53
Table A.7 – I/O units and interface (external communication).53
Table A.8 – Data paths (internal communication) .54
Table A.9 – Power supply .54
Table A.10 – Program sequence (watch-dog).55
Table A.11 – Clock .55
Table A.12 – Communication and mass-storage .55
Table A.13 – Sensors .56
Table A.14 – Final elements (actuators).56
Table A.15 – Techniques and measures to control systematic failures caused by
hardware design .58

– 4 – 61508-2 © IEC:2010
Table A.16 – Techniques and measures to control systematic failures caused by
environmental stress or influences.59
Table A.17 – Techniques and measures to control systematic operational failures.60
Table A.18 – Effectiveness of techniques and measures to control systematic failures .61
Table B.1 – Techniques and measures to avoid mistakes during specification of
E/E/PE system design requirements (see 7.2) .63
Table B.2 – Techniques and measures to avoid introducing faults during E/E/PE
system design and development (see 7.4) .64
Table B.3 – Techniques and measures to avoid faults during E/E/PE system
integration (see 7.5).65
Table B.4 – Techniques and measures to avoid faults and failures during E/E/PE
system operation and maintenance procedures (see 7.6).66
Table B.5 – Techniques and measures to avoid faults during E/E/PE system safety
validation (see 7.7) .67
Table B.6 – Effectiveness of techniques and measures to avoid systematic failures.68
Table E.1 – Techniques and measures that increase β .79
B-IC
Table E.2 – Techniques and measures that decrease β .80
B-IC
Table F.1 – Techniques and measures to avoid introducing faults during ASIC’s design
and development – full and semi-custom digital ASICs (see 7.4.6.7).83
Table F.2 – Techniques and measures to avoid introducing faults during ASIC design
and development: User programmable ICs (FPGA/PLD/CPLD) (see 7.4.6.7) .86

61508-2 © IEC:2010 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FUNCTIONAL SAFETY OF ELECTRICAL/ELECTRONIC/
PROGRAMMABLE ELECTRONIC SAFETY-RELATED SYSTEMS –

Part 2: Requirements for electrical/electronic/programmable
electronic safety-related systems

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
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agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61508-2 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.
It has the status of a basic safety publication according to IEC Guide 104.

– 6 – 61508-2 © IEC:2010
The text of this standard is based on the following documents:
FDIS Report on voting
65A/549/FDIS 65A/573/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 maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
61508-2 © IEC:2010 – 7 –
INTRODUCTION
Systems comprised of electrical and/or electronic elements have been used for many years to
perform safety functions in most application sectors. Computer-based systems (generically
referred to as programmable electronic systems) are being used in all application sectors to
perform non-safety functions and, increasingly, to perform safety functions. If computer
system technology is to be effectively and safely exploited, it is essential that those
responsible for making decisions have sufficient guidance on the safety aspects on which to
make these decisions.
This International Standard sets out a generic approach for all safety lifecycle activities for
systems comprised of electrical and/or electronic and/or programmable electronic (E/E/PE)
elements that are used to perform safety functions. This unified approach has been adopted
in order that a rational and consistent technical policy be developed for all electrically-based
safety-related systems. A major objective is to facilitate the development of product and
application sector international standards based on the IEC 61508 series.
NOTE 1 Examples of product and application sector international standards based on the IEC 61508 series are
given in the Bibliography (see references [1], [2] and [3]).
In most situations, safety is achieved by a number of systems which rely on many
technologies (for example mechanical, hydraulic, pneumatic, electrical, electronic,
programmable electronic). Any safety strategy must therefore consider not only all the
elements within an individual system (for example sensors, controlling devices and actuators)
but also all the safety-related systems making up the total combination of safety-related
systems. Therefore, while this International Standard is concerned with E/E/PE safety-related
systems, it may also provide a framework within which safety-related systems based on other
technologies may be considered.
It is recognized that there is a great variety of applications using E/E/PE safety-related
systems in a variety of application sectors and covering a wide range of complexity, hazard
and risk potentials. In any particular application, the required safety measures will be
dependent on many factors specific to the application. This International Standard, by being
generic, will enable such measures to be formulated in future product and application sector
international standards and in revisions of those that already exist.
This International Standard
– considers all relevant overall, E/E/PE system and software safety lifecycle phases (for
example, from initial concept, though design, implementation, operation and maintenance
to decommissioning) when E/E/PE systems are used to perform safety functions;
– has been conceived with a rapidly developing technology in mind; the framework is
sufficiently robust and comprehensive to cater for future developments;
– enables product and application sector international standards, dealing with E/E/PE
safety-related systems, to be developed; the development of product and application
sector international standards, within the framework of this standard, should lead to a high
level of consistency (for example, of underlying principles, terminology etc.) both within
application sectors and across application sectors; this will have both safety and economic
benefits;
– provides a method for the development of the safety requirements specification necessary
to achieve the required functional safety for E/E/PE safety-related systems;
– adopts a risk-based approach by which the safety integrity requirements can be
determined;
– introduces safety integrity levels for specifying the target level of safety integrity for the
safety functions to be implemented by the E/E/PE safety-related systems;
NOTE 2 The standard does not specify the safety integrity level requirements for any safety function, nor does it
mandate how the safety integrity level is determined. Instead it provides a risk-based conceptual framework and
example techniques.
– 8 – 61508-2 © IEC:2010
– sets target failure measures for safety functions carried out by E/E/PE safety-related
systems, which are linked to the safety integrity levels;
– a low demand mode of operation, the lower limit is set at an average probability of a
–5
dangerous failure on demand of 10 ;
– a high demand or a continuous mode of operation, the lower limit is set at an average
–9 –1
frequency of a dangerous failure of 10 [h ];
NOTE 3 A single E/E/PE safety-related system does not necessarily mean a single-channel architecture.
NOTE 4 It may be possible to achieve designs of safety-related systems with lower values for the target safety
integrity for non-complex systems, but these limits are considered to represent what can be achieved for relatively
complex systems (for example programmable electronic safety-related systems) at the present time.
– sets requirements for the avoidance and control of systematic faults, which are based on
experience and judgement from practical experience gained in industry. Even though the
probability of occurrence of systematic failures cannot in general be quantified the
standard does, however, allow a claim to be made, for a specified safety function, that the
target failure measure associated with the safety function can be considered to be
achieved if all the requirements in the standard have been met;
– introduces systematic capability which applies to an element with respect to its confidence
that the systematic safety integrity meets the requirements of the specified safety integrity
level;
– adopts a broad range of principles, techniques and measures to achieve functional safety
for E/E/PE safety-related systems, but does not explicitly use the concept of fail safe.
However, the concepts of “fail safe” and “inherently safe” principles may be applicable and
adoption of such concepts is acceptable providing the requirements of the relevant
clauses in the standard are met.

61508-2 © IEC:2010 – 9 –
FUNCTIONAL SAFETY OF ELECTRICAL/ELECTRONIC/
PROGRAMMABLE ELECTRONIC SAFETY-RELATED SYSTEMS –

Part 2: Requirements for electrical/electronic/programmable
electronic safety-related systems

1 Scope
1.1 This part of the IEC 61508 series
a) is intended to be used only after a thorough understanding of IEC 61508-1, which provides
the overall framework for the achievement of functional safety;
b) applies to any safety-related system, as defined by IEC 61508-1, that contains at least
one electrical, electronic or programmable electronic element;
c) applies to all elements within an E/E/PE safety-related system (including sensors,
actuators and the operator interface);
d) specifies how to refine the E/E/PE system safety requirements specification, developed in
accordance with IEC 61508-1 (comprising the E/E/PE system safety functions
requirements specification and the E/E/PE system safety integrity requirements
specification), into the E/E/PE system design requirements specification;
e) specifies the requirements for activities that are to be applied during the design and
manufacture of the E/E/PE safety-related systems (i.e. establishes the E/E/PE system
safety lifecycle model) except software, which is dealt with in IEC 61508-3 (see Figures 2
to 4). These requirements include the application of techniques and measures that are
graded against the safety integrity level, for the avoidance of, and control of, faults and
failures;
f) specifies the information necessary for carrying out the installation, commissioning and
final safety validation of the E/E/PE safety-related systems;
g) does not apply to the operation and maintenance phase of the E/E/PE safety-related
systems – this is dealt with in IEC 61508-1 – however, IEC 61508-2 does provide
requirements for the preparation of information and procedures needed by the user for the
operation and maintenance of the E/E/PE safety-related systems;
h) specifies requirements to be met by the organisation carrying out any modification of
the E/E/PE safety-related systems;
NOTE 1 This part of IEC 61508 is mainly directed at suppliers and/or in-company engineering departments, hence
the inclusion of requirements for modification.
NOTE 2 The relationship between IEC 61508-2 and IEC 61508-3 is illustrated in Figure 4.
i) does not apply for medical equipment in compliance with the IEC 60601 series.
1.2 IEC 61508-1, IEC 61508-2, IEC 61508-3 and IEC 61508-4 are basic safety publications,
although this status does not apply in the context of low complexity E/E/PE safety-related
systems (see 3.4.3 of IEC 61508-4). As basic safety publications, they are intended for use by
technical committees in the preparation of standards in accordance with the principles
contained in IEC Guide 104 and ISO/IEC Guide 51. IEC 61508-1, IEC 61508-2, IEC 61508-3
and IEC 61508-4 are also intended for use as stand-alone standards. The horizontal safety
function of this international standard does not apply to medical equipment in compliance with
the IEC 60601 series.
1.3 One of the responsibilities of a technical committee is, wherever applicable, to make use
of basic safety publications in the preparation of its publications. In this context, the
requirements, test methods or test conditions of this basic safety publication will not apply

– 10 – 61508-2 © IEC:2010
unless specifically referred to or included in the publications prepared by those technical
committees.
NOTE The functional safety of an E/E/PE safety-related system can only be achieved when all related
requirements are met. Therefore, it is important that all related requirements are carefully considered and
adequately referenced.
1.4 Figure 1 shows the overall framework of the IEC 61508 series and indicates the role that
IEC 61508-2 plays in the achievement of functional safety for E/E/PE safety-related systems.
Annex A of IEC 61508-6 describes the application of IEC 61508-2 and IEC 61508-3.

61508-2 © IEC:2010 – 11 –
Figure 1 – Overall framework of the IEC 61508 series

– 12 – 61508-2 © IEC:2010
2 Normative references
The following referenced documents are indispensable for the application 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.
IEC 60947-5-1, Low-voltage switchgear and controlgear – Part 5-1: Control circuit devices
and switching elements – Electromechanical control circuit devices
IEC/TS 61000-1-2, Electromagnetic compatibility (EMC) – Part 1-2: General – Methodology
for the achievement of functional safety of electrical and electronic systems including
equipment with regard to electromagnetic phenomena
IEC 61326-3-1, Electrical equipment for measurement, control and laboratory use – EMC
requirements – Part 3-1: Immunity requirements for safety-related systems and for equipment
intended to perform safety-related functions (functional safety) – General industrial
applications
IEC 61508-1: 2010, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 1: General requirements
IEC 61508-3: 2010, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 3: Software requirements
IEC 61508-4: 2010, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 4: Definitions and abbreviations
IEC 61508-7: 2010, Functional safety of electrical/electronic/programmable electronic safety
related systems – Part 7: Overview of techniques and measures
IEC 61784-3, Industrial communication networks – Profiles – Part 3: Functional safety
fieldbuses – General rules and profile definitions
IEC 62280-1, Railway applications – Communication, signalling and processing systems –
Part 1: Safety-related communication in closed transmission systems
IEC 62280-2, Railway applications – Communication, signalling and processing systems –
Part 2: Safety-related communication in open transmission systems
IEC Guide 104:1997, The preparation of safety publications and the use of basic safety
publications and group safety publications
ISO/IEC Guide 51:1999, Safety aspects – Guidelines for their inclusion in standards
EN 50205, Relays with forcibly guided (mechanically linked) contacts
3 Definitions and abbreviations
For the purposes of this document, the definitions and abbreviations given in IEC 61508-4
apply.
4 Conformance to this standard
The requirements for conformance to this standard are as detailed in Clause 4 of
IEC 61508-1.
61508-2 © IEC:2010 – 13 –
5 Documentation
The requirements for documentation are as detailed in Clause 5 of IEC 61508-1.
6 Management of functional safety
The requirements for management of functional safety are as detailed in Clause 6 of
IEC 61508-1.
7 E/E/PE system safety lifecycle requirements
7.1 General
7.1.1 Objectives and requirements – general
7.1.1.1 This subclause sets out the objectives and requirements for the E/E/PE system
safety lifecycle phases.
NOTE The objectives and requirements for the overall safety lifecycle, together with a general introduction to the
structure of the standard, are given in IEC 61508-1.
7.1.1.2 For all phases of the E/E/PE system safety lifecycle, Table 1 indicates
– the objectives to be achieved;
– the scope of the phase;
– a reference to the subclause containing the requirements;
– the required inputs to the phase;
– the outputs required to comply with the subclause.
7.1.2 Objectives
7.1.2.1 The first objective of the requirements of this subclause is to structure, in a
systematic manner, the phases in the E/E/PE system safety lifecycle that shall be considered
in order to achieve the required functional safety of the E/E/PE safety-related systems.
7.1.2.2 The second objective of the requirements of this subclause is to document all
information relevant to the functional safety of the E/E/PE safety-related systems throughout
the E/E/PE system safety lifecycle.
7.1.3 Requirements
7.1.3.1 The E/E/PE system safety lifecycle that shall be used in claiming conformance with
this standard is that specified in Figure 2. A detailed V-model of the ASIC development
lifecycle for the design of ASICs (see IEC 61508-4, 3.2.15) is shown in Figure 3. If another
E/E/PE system safety lifecycle or ASIC development lifecycle is used, it shall be specified as
part of the management of functional safety activities (see Clause 6 of IEC 61508-1), and all
the objectives and requirements of each subclause of IEC 61508-2 shall be met.
NOTE 1 The relationship between and scope for IEC 61508-2 and IEC 61508-3 are shown in Figure 4.
NOTE 2 There are significant similarities between the ASIC and the software design processes. IEC 61508-3
recommends the V-model for designing safety-related software. The V-model requires a clearly structured design
process and a modular software structure for avoiding and controlling systematic faults. The ASIC development
lifecycle for the design of ASICs in Figure 3 follows this model. At first the requirements for the ASIC specification
are derived from the system requirements. ASIC architecture, ASIC design and module design follow. The results
of each step on the left-hand side of the V become the input to the next step, and are also fed back to the
preceding step for iteration where appropriate, until the final code is created. This code is verified against the
corresponding design through post-layout simulation, module testing, module integration testing and verification of
the complete ASIC. The results of any step may necessitate a revision to any of the preceding steps. Finally, the
ASIC is validated after its integration into the E/E/PE safety-related system.

– 14 – 61508-2 © IEC:2010
7.1.3.2 The procedures for management of functional safety (see Clause 6 of IEC 61508-1)
shall run in parallel with the E/E/PE system safety lifecycle phases.
7.1.3.3 Each phase of the E/E/PE system safety lifecycle shall be divided into elementary
activities, with the scope, inputs and outputs specified for each phase (see Table 1).
7.1.3.4 Unless justified as part of the management of functional safety activities (see
Clause 6 of IEC 61508-1), the outputs of each phase of the E/E/PE system safety lifecycle
shall be documented (see Clause 5 of IEC 61508-1).
7.1.3.5 The outputs for each E/E/PE system safety lifecycle phase shall meet the objectives
and requirements specified for each phase (see 7.2 to 7.9).

NOTE 1 See also IEC 61508-6, A.2 b).
NOTE 2 This figure shows only those phases of the E/E/PE system safety lifecycle that are within the realisation
phase of the overall safety lifecycle. The complete E/E/PE system safety lifecycle will also contain instances,
specific to the E/E/PE safety-related system, of the subsequent phases of the overall safety lifecycle (Boxes 12 to
16 in Figure 2 of IEC 61508-1).
Figure 2 – E/E/PE system safety lifecycle (in realisation phase)

61508-2 © IEC:2010 – 15 –
ASIC Validation
E/E/PE system ASIC safety
Validation
safety requirements requirements Validated
testing
specification specification ASIC
E/E/PE system ASIC Verification of
architecture architecture complete ASIC
ASIC design and Module
behavioural integration
modelling testing
Module Module
design testing
Synthesis,
Post-layout
placement and
simulation
routing
Key
Output
Final coding
Verification
Figure 3 – ASIC development lifecycle (the V-Model)

Scope of
E/E/PE system IEC 61508-2
E/E/PE system E/E/PE
design requirements
design requirements system
specification
specification architecture
Hardware safety requirements
specification
Scope of Software safety
requirements
Programmable Non-programmable
IEC 61508-3
electronic hardware hardware
Software design Programmable Non-programmable
and electronics design hardware design
development and development and development
E/E/PE
E/E/PE
Programmable electronics
system
integration (hardware and
system
software) integration
integration
Figure 4 – Relationship between and scope of IEC 61508-2 and IEC 61508-3

– 16 – 61508-2 © IEC:2010
Table 1 – Overview – realisation phase of the E/E/PE system safety lifecycle
Safety lifecycle phase
Require-
or activity
ments
Objectives Scope Inputs Outputs
Figure
sub-
2 box Title
clause
number
E/E/PE system design
10.1 E/E/PE system To specify the design E/E/PE 7.2.2 E/E/PE system safety
design requirements for each safety- requirements requirements
requirements E/E/PE safety-related related specification specification, describing
specification system, in terms of the system (see IEC 61508-1, the equipment and
subsystems and elements 7.10) architectures for the
(see 7.10.2 of IEC 61508- E/E/PE system
1)
10.2 E/E/PE system To plan the validation of E/E/PE 7.3.2 E/E/PE system safety Plan for the safety
safety the safety of the E/E/PE safety- requirements validation
validation safety-related system related specification and of the E/E/PE safety-
planning system E/E/PE system related systems
design requirements
specification
10.3 To design and develop E/E/PE 7.4.2 E/E/PE system Design of the E/E/PE
the E/E/PE safety-related safety- to design requirements safety related systems
E/E/PE system
system (including ASICs if related 7.4.11 specification in conformance with the
design &
appropriate) to meet the system E/E/PE system design
development
E/E/PE system design requirements
including
requirements specification specification
ASICs &
(with respect to the safety
software Plan for the E/E/PE
functions requirements
system integration test
and the safety integrity
(see Figure 3
requirements (see 7.2))
& also PE system architectural
IEC 61508-3) information as an input

to the software
requirements
specification
10.4 E/E/PE system To integrate and test the E/E/PE 7.5.2 E/E/PE system Fully functioning E/E/PE
integration E/E/PE safety-related safety- design safety-related systems
system related in conformance with the
E/E/PE system
system E/E/PE system design
integration test plan
Results of E/E/PE
Programmable
system integration tests
electronics hardware
and software
10.5 E/E/PE system To develop procedures to E/E/PE 7.6.2 E/E/PE system E/E/PE system
installation, ensure that the required safety- design requirements installation,
commissioning functional safety of the related specification commissioning,
, operation E/E/PE safety-related system operation and
E/E/PE system
and system is maintained maintenance
EUC design
maintenance during operation and procedures for each
procedures maintenance indi
...