Security relay and security-oriented communication system

摘要

The system has a safety relay (2) for switching on and off operations of a connectable load (4). The safety relay is connected to two signal inputs (IN1,IN2) of a control unit (1). The safety relay comprises a load circuit that is formed by two parallel-connected switching elements (251,252) that are switched on or off in response to a drive signal output by a control logic (220). A diagnostic device (240) is provided for monitoring errors in the load circuit. A signaling device (210) is adapted for providing variable impedance upon detection of an error by diagnostic device.