PLCopen safety specification

Within the context of PLCopen, a specification for standardizing safety-focused application software was worked out by the PLCopen members – most of them are leading manufacturers of safety controllers, developers of programming tools – together with external organizations (BGIA, TÜV Rheinland).

Content of the specification

Essentially, the specification describes the standardization of safe function blocks and the standardized use of these blocks in an engineering software tool. The most important topics are:

• Safe function blocks

• Safety data types

Why standardization?

In the past, the embedded software (runtime system, operating system) and the hardware of safety-relevant automation solutions were already intensely proofed by certification authorities. However, the functionality of a safety controller can only be completely grasped together with the related engineering software. But particularly in the field of safety-related application software, there were no integrated requirements up to now.

This resulted in the fact that many of today's engineering software tools have a non-uniform user interface and operation and different safety function characteristics. Another aggravating fact is that the existing engineering software mostly does not fulfill current safety technology quality standards (such as the IEC 61508) because, within the scope of the former standards DIN VDE 0801 and EN954-1, only little attention was paid to the application software.

As a result, PLC programmers as well as certification authorities must deal again and again with the most different safety logic occurrences. In the user's view, the definition of a uniform standard for safety-relevant application software is a right and important step.