PLCopen releases version 2.0 of Safety Specification Part 1 |

PLCopen releases version 2.0 of Safety Specification Part 1

PLCopen releases version 2.0 of  Safety Specification Part 1

November 28, 2018 - In February 2006 PLCopen published their Safety Specification Part 1 - Concepts and Function Blocks for Safety Functions, followed by user guidelines and additional parts.

The original document describes the functionalities as well as extensive state diagrams which add to the understanding, references to the applicable standards, description of error behavior, functional checks, and error codes, and identifies different programming levels. As such it is an ideal platform for implementers. For users, additional information on safety devices, connections and wiring is of course needed.

After so many years, an update was needed resulting in Version 2.0 of this document which was published earlier this year. This version contains many changes:

  1. Incorporates the original Part 3, especially the section on diagnostics and the additional 5 function blocks.
  2. In addition, the Structured Text language ST is added, as well as additional datatypes and functionalities.
  3. All the original function blocks have been updated w.r.t. diagnostic codes, the outputs safety demand and reset requested, and the reset functionality has been extended to trailing edge via the definition of a new function block.
  4. Also there are 3 motion related function blocks 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:

  1. Distinction between safety and non-safety functionalities
  2. Use of applicable programming languages and language subsets
  3. Use of validated software blocks
  4. Use of applicable programming guidelines
  5. Use of recognized error-reducing measures for the lifecycle of the safety-related software

For users, the effort to fulfill these high requirements should be reduced. This can be done using standardized solutions, which enable typical functionalities to be implemented easily. The 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.

The PLCopen technical working group produced this specification to meet the basic safety requirements. To achieve this, PLCopen Committees identified two levels:

  1. Integration of standard procedures in the development environment
  2. Standardization in the look and feel of safety function blocks

This includes:

  1. Representation of the software architecture
  2. Definition of the programming languages
  3. Presentation of safety-related data types
  4. Definition of language subsets
  5. Definition of user levels for easy programming and error prevention
  6. Error handling and diagnostic concept
  7. Definition of a generic safety-related function block
  8. The definition of a set of 22 safety-related function blocks
  9. The definition of a PLCopen compliance procedure combined with the use of the PLCopen Safety logo

Basically the resulting document consists of three parts:

  1. Reduction in programming languages and functions, to enable safety-related application programs to be created
  2. General rules for safety-related function blocks
  3. The definition of a set of function blocks with safety-related functions

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

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