Description     Claims     Drawing  

US5794167A   [0002] 
US2004136487A1   [0003] 
JPH634269B   [0008] 

Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 6: Guidelines on the application of IEC 61508-2   [0009] 
International Electrotechnical Commission   [0009] 
Safety Instrumented System and ProSafe Diagnostic Functions   [0009]