PSSu H FS SN SD M12-R 315086 Communication modules PSSuniversal I/O, for implementation of safety-related and standard applications in the automation system PSS 4000. PSSu, head module, control system PSSu I/O, failsafe and standard, PL e, SIL CL 3, 2 M12 female connectors, 4-pin D-coded, SafetyNET p RTFN, for railway applications.