Safety circuit assembly for switching on or off a hazardous system in a failsafe manner

A signaling device configured for connection to an evaluating device in order to form a safety circuit assembly for switching on or switching off a hazardous system in a failsafe manner, the signaling device comprising:

• an actuator configured to be transferred between a defined first state and a second state,
• a pair of connecting terminals for connecting a first line and a second line, said first and second lines forming a single pair of lines, and
• at least one pulse generator designed for receiving a first defined pulse signal from the evaluating device via said single pair of lines, and for generating a second defined pulse signal in response to the first defined pulse signal,
• wherein the second pulse signal is a predefined replica of the first pulse signal, and
• wherein the at least one pulse generator transmits the second pulse signal to the evaluating device using said single pair of lines, only when the actuator is in the defined first state.

An evaluating device configured for connection to a signaling device in order to form a safety circuit assembly for switching on or switching off a hazardous system in a failsafe manner, the evaluating device comprising:

• a first pair of connecting terminals for connecting a first and a second line which together form a pair of lines,
• at least two further connecting terminals for outputting a failsafe switching signal for shutting down the hazardous system, and
• at least one evaluating circuit for generating a defined first pulse signal on said pair of lines, for receiving a defined second pulse signal from the signaling device via said pair of lines, and for comparing the defined second pulse signal and the defined first pulse signal,
• wherein the evaluating circuit is further configured to generate the failsafe switching signal in dependence on whether or not the defined second pulse signal is a predefined replica of the defined first pulse signal.