Overview
IEC TS 61508-3-1:2016 is a technical specification developed by the International Electrotechnical Commission (IEC) that establishes requirements for the reuse of pre-existing software elements in electrical, electronic, or programmable electronic (E/E/PE) safety-related systems. This standard addresses the implementation of all or part of a safety function using pre-existing software for systems targeting Safety Integrity Levels (SIL) 1 or 2. IEC TS 61508-3-1:2016 supplements the IEC 61508 series, particularly with regard to claiming proven-in-use for software elements as part of functional safety applications.
The standard is especially relevant to engineers, integrators, and safety professionals who are responsible for certifying or developing E/E/PE safety systems. By following its guidelines, organizations can optimize the development lifecycle by leveraging existing software while maintaining compliance with international safety benchmarks.
Key Topics
- Proven-in-Use Justification: Defines criteria for claiming that pre-existing software is sufficiently reliable based on its prior operational experience.
- Documentation and Evidence: Stipulates detailed requirements for documenting prior use, configuration, operational profiles, and analysis of previous operation.
- Scope Limitation: Applies only to safety functions up to SIL 2, reflecting current limitations in proven-in-use methods for higher integrity levels.
- Failure Detection and Reporting: Requires comprehensive evidence that all failures during prior use were reliably detected and properly reported.
- Compatibility and Configuration: Necessitates assessment of hardware, software, libraries, compilers, and operational conditions to ensure consistency with previous use.
- Restriction After Modification: Establishes that any modification to proven-in-use software invalidates its status, requiring compliance with new software development standards before reuse.
Applications
IEC TS 61508-3-1:2016 is vital for the industrial automation and process control sectors, particularly where functional safety and regulatory compliance are paramount. Typical applications include:
- Industrial Process Control Systems: Enables reuse of certified software components within programmable logic controllers (PLCs) and distributed control systems (DCS) for safety functions.
- Machine Safety: Facilitates integration of previously validated safety software in machinery, simplifying certification for SIL 1 and SIL 2 functions.
- Safety Instrumented Systems (SIS): Supports claims of functional safety compliance within chemical, petrochemical, and energy industries by allowing reuse of software in safety-critical applications.
- Embedded Safety Devices: Allows manufacturers to incorporate trusted software elements into new products while demonstrating ongoing conformity to international safety standards.
By ensuring that proven-in-use software elements are thoroughly assessed and documented, organizations can reduce development costs, leverage existing expertise, and maintain robust safety integrity in critical systems.
Related Standards
For comprehensive functional safety and software reuse strategies, IEC TS 61508-3-1:2016 should be employed alongside the following standards:
- IEC 61508-3:2010 - Functional safety of E/E/PE safety-related systems - Part 3: Software requirements
- IEC 61508-2:2010 - Functional safety of E/E/PE safety-related systems - Part 2: Requirements for E/E/PE safety-related systems
- IEC 61508-4:2010 - Functional safety of E/E/PE safety-related systems - Part 4: Definitions and abbreviations
These related standards provide the foundational terminology, system requirements, and procedural guidance necessary for implementing robust safety-related software reuse within the IEC 61508 framework.
Keywords: IEC TS 61508-3-1, functional safety, proven-in-use, pre-existing software, safety function, SIL 1, SIL 2, E/E/PE systems, software reuse, IEC standards, documentation, failure detection, safety integrity.