IEC 61508

IEC 61508 (Functional Safety of Electrical / Electronic / Programmable Electronic Safety-related systems) is a generic functional safety standard which may be applicable to all cases where programmable devices are used to control the functioning of systems where safety is or may be a consideration.

A system to which IEC 61508 is applicable may have varying levels of risk to the user or different safety requirements. To accommodate this IEC 61508 has four Safety Integrity Levels (SIL 1 – 4), with SIL 4 representing projects with the most rigorous safety requirements.

Fitness for purpose litigation against companies and individuals is now an increasing risk. IEC 61508 is a technical standard used by lawyers to interpret laws. The relevant law in question for Europe is the General Product Safety Directive 2001/95/EC (GPSD). This states that the product creator has the responsibility to develop a safety critical product in a way which is compliant with ‘State-of-the-Art’ development principles. ‘State-of-the-Art’ simply refers to commonly accepted best practices, which in the case of electronic saftey related systems are now embodied in IEC 61508:2010 (or the previously mentioned standards derived from it which focus on specific industries). Where companies fail to employ accepted industry practices, they cannot use the “State-of-the-Art” legal defence against such litigation.

ANALYSE STATIQUE

Software testing for IEC 61508 compliance

IEC 61508 Section 3, Table A.5 recommends software module testing and integration. The Cantata testing tool enables developers to automate their unit and integration testing and to verify IEC 61508 compliant code on host native and embedded target platforms.

Cantata helps accelerate compliance with the standard’s software testing requirements by automating:

IEC 61508 Table A.3 – Software design and development – support tools and programming language

IEC 61508 Table A.4 – Software design and development – detailed design

IEC 61508 Table A.5 – Software design and development – software module testing and integration

IEC 61508 Table A.6 – Programmable electronics integration (hardware and software)

IEC 61508 Table A.7 – Software aspects of system safety validation

IEC 61508 Table A.8 – Modification

IEC 61508 Table A.9 – Software Verification

IEC 61508 Table B.1 – Design and coding standards

IEC 61508 Table B.2 – Dynamic analysis and testing

IEC 61508 Table B.3 – Functional and black-box testing

IEC 61508 Table B.5 – Modelling

IEC 61508 Table B.6 – Performance testing

IEC 61508 Table B.7 – Semi-formal methods

IEC 61508 Table B.9 – Modular approach

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Static analysis for IEC 61508 compliance

Part 3 of IEC 61508 addresses the software requirements of a safety-related system mandating the use of better development processes, including the use of coding standards such as MISRA to encourage further gains in software quality. It includes several tables that define the methods that must be considered in order to achieve compliance with the standard.

The following tables identify where Static Analysis can be used to ensure and demonstrate compliance with IEC 61508.

IEC 61508 Section 6 – Additional Requirements for Management of Safety-Related Software

IEC 61508 Table 1 – Software Safety Lifecycle – Overview

IEC 61508 Section 7.4.4 – Requirements for Support Tools, Including Programming Languages

IEC 61508 Table A.2 – Software Design and Development – Software Architecture Design

IEC 61508 Table A.3 – Software design and development – support tools and programming language (copy 1)

IEC 61508 Table A.4 – Software design and development – Detailed design

IEC 61508 Table A.9 – Software Verification

IEC 61508 Table B.1 – Design and coding standards

IEC 61508 Table B.8 – Design and coding standards

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