/community-hubs/deltav-community-connect/b/delta-vweblog/posts/defense-in-depth-approach-helps-prevent-unauthorized-changes-in-safety-logicOne of the main concerns from users of process safety systems is how to effectively protect the SIS against unauthorized changes of the safety logic. The traditional protection approach is based on a key switch on the safety PLC; before somebody can alteren-USTelligent Community 13