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 used together with the related engineering software. But particularly in the field of safety-related application software, there are no integrated requirements. This results in the fact that a large part of today's engineering software tools have a non-uniform user interface and operation and different safety function characteristics. Another aggravating fact is that most of the existing engineering software does not fulfill current safety technology quality standards such as the IEC 61508. The reason for this dates back several years, 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.
Within the context of the 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 or according programming tools – together with external organizations (BGIA, TÜV Rheinland). A preliminary version of this specification was presented at the Hanover Fair for the first time. The aim is to release this specification by the BGIA and TÜV Rheinland until the SPS/IPC Drives Fair in Nuremberg. Essentially, the specification describes the standardization of safe function blocks and the standardized use of these blocks in an engineering software tool. The following sections describe the most important contents in an exemplary way.
These include:
• Safe function blocks
• Safety data types
• Recommendations for programming guide lines
• Graded user levels