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PLC/PAC with Secure Partitioning
2

PLC/PAC with Secure Partitioning

PLC/PAC with Secure Partitioning

(OP)
I'm trying to find a commercial PLC or PAC that will support multiple programs at different safety levels to execute on a single processor.  

That is, I'm looking for a run-time systems which guarantees that any failure resulting from a defect in a program operating at a lower safety level can not, under any circumstance, disrupt the operation of the higher safety level functions.

I know there are various RTOSes out there that claim to support such a design (e.g. Green Hills Integrity -178B) for embedded processing, but we typically use PLCs in our control system designs, so I'm hoping to find a PLC (or similar) that supports this.

Does anybody know of any PLCs or PACs that support this?
 

RE: PLC/PAC with Secure Partitioning

I'm not sure exactly how they work, but I know Siemens, and several more I am sure, now have PLCs that are rated for safety service, and qualify as a promary and redundant processor in a single unit.

RE: PLC/PAC with Secure Partitioning

A-B GuardLogix will allow both safety level programs and non-safety level programs co-exist on the same processor.

Generally speaking, most PLCs only support one single executable program. That program may have many different independent parts, and in some cases the various parts be executed asynchronisly of one another. However a fault in one part of the program, if not caught, will cause the processor to fault stopping all programs.

The features you are looking for probably only exist on higher level controllers such as soft PLCs or controllers.

RE: PLC/PAC with Secure Partitioning

Siemens S7-300F and 400F processors are exactly what you are describing. They have separate programs running simultaneously in the same processor, one for Safety programs, one for "regular" programs. The regular program can receive information from the Safety program, but in no way disrupts or interferes with the safety program operation.
Simatic Safety Systems
 


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