[ RadSafe ] Interlock question

[Bob May]

Excellent discussion on interlock design and functionality. There is a Rockwell publication at the following link: http://discover.rockwellautomation.com/Files/PLC-vs-Safety-PLC-Fundamental-and-Significant-Differences.pdf that discusses PLCs versus Safety PLCs. It won't change your mind if you are not a fan of electronic systems but it is informative and points to the international standard IEC 61508, "Functional safety of electrical/electronic/programmable electronic safety-related systems".
Bob