In the process industry safe coupling relays are often used for coupling safety related signals, for example output signals of a safe control system to the periphery. The use of simple relays would result in the interruption of the safety chain and therefore a safe shutdown in case of failure could not be guaranteed. This problem can be solved by using safe coupling relays. Redundantly built, self-monitoring coupling relays allow the standardized coupling of safety related signals up to SIL 3 / PL e.