PLCopen Releases Version 2.0 of the Safety Specification Part1

By Chantal Polsonetti

Company and Product News

PLCopen published Version 2.0 of their Safety Specification Part 1 - Concepts and Function Blocks for Safety Functions.  This specification describes functionalities and includes extensive state diagrams, references to the applicable standards, description of error behavior, functional checks, and error codes, and identifies different programming levels.. Version 2.0 contains the following changes:

  • Incorporates the original Part 3, especially the section on diagnostics and the additional 5 function blocks
  • Adds the Structured Text language ST as well as additional datatypes and functionalities
  • Updates to all the original function blocks, including diagnostic codes, the outputs safety demand and reset requested, and the reset functionality
  • Three motion related function blocks were removed and added to a separate document on SafeMotion.


The common basic requirements of a safety application for machine builders within all applicable safety standards are:

  • Distinction between safety and non-safety functionalities
  • Use of applicable programming languages and language subsets
  • Use of validated software blocks
  • Use of applicable programming guidelines
  • Use of recognized error-reducing measures for the lifecycle of the safety-related software


Standardization of function blocks and integration and support from software tools enables programmers to integrate safety in their applications from the beginning, without adversely affecting their functions and performance, and without adding costs.


PLCopen produced this specification to meet basic safety requirements, including:

  • Representation of the software architecture
  • Definition of the programming languages
  • Presentation of safety-related data types
  • Definition of language subsets
  • Definition of user levels for easy programming and error prevention
  • Error handling and diagnostic concept
  • Definition of a generic safety-related function block
  • Definition of a set of 22 safety-related function blocks
  • Definition of a PLCopen compliance procedure combined with the use of the PLCopen Safety logo


This new version 2.0 of the PLCopen Safety specification Part 1 can be downloaded from

Engage with ARC Advisory Group