What is BS EN 61131-6 - Programmable controllers for functional safety about?
BS EN 61131-6 is the sixth part of the multiple series document that specifies requirements for programmable controllers (PLCs) and their associated peripherals, as defined in Part 1, which are intended to be used as the logic subsystem of an electrical/electronic/programmable electronic (E/E/PE) safety-related system. A programmable controller and its associated peripherals complying with the requirements of this part is considered suitable for use in an E/E/PE safety-related system and is identified as a functional safety programmable logic controller (FS-PLC). An FS-PLC is generally a hardware (HW) / software (SW) subsystem. An FS-PLC may also include software elements, for example, predefined function blocks.
Note 1: BS EN 61131-6 does not cover general safety requirements for an FS-PLC such as requirements related to electric shock and fire hazards specified in IEC 61131-2.
Note 2: BS EN 61131-6 applies to an FS-PLC with a Safety Integrity Level (SIL) capability not greater than SIL 3.
Who is BS EN 61131-6 - Programmable controllers for functional safety for?
BS EN 61131-6 on programmable controllers for functional safety is useful for:
- Software programmers/engineers 
- The IT industries
- Users of programmable controller systems
- Implementers of programming and debugging tools
- Programming language implementers
Why should you use BS EN 61131-6 - Programmable controllers for functional safety?
An E/E/PE safety-related system generally consists of sensors, actuators, software and a logic subsystem. BS EN 61131-6 is a product-specific implementation of the requirements of the IEC 61508 series and conformity to this part fulfils all of the applicable requirements of the IEC 61508 series related to FS-PLCs.
BS EN 61131-6 addresses only the functional safety and safety integrity requirements of an FS-PLC when used as part of an E/E/PE safety-related system. BS EN 61131-6 defines the functional safety requirements of the overall E/E/PE safety-related system.
Overall, BS EN 61131-6 will help you to:
- To establish and describe the safety life-cycle elements of an FS-PLC, in harmony with the general safety life cycle identified in IEC 61508-1, -2 and -3
- To establish and describe the requirements for FS-PLC HW and SW that relate to the functional safety and safety integrity requirements of an E/E/PE safety-related system
- To establish evaluation methods for FS-PLC parameters/criteria
- To establish the definitions and identify the principal characteristics relevant to the selection and application of FS-PLCs and their associated peripherals
