Safety relay and safety-related communication system

摘要

A safety-related communication system includes a safety relay with signal inputs of an input signal current circuit that connect the safety relay to a control device for monitoring the input signal circuit. The safety relay also includes at least two load outputs of a load current circuit for connecting to a load. Switching elements are connected in parallel and configured to switch the load current circuit on or off based on an activation signal at the input signal current circuit. A diagnostic device monitors faults in the load current circuit and/or the safety relay. A signaling device connected to the signal inputs provides an impedance for the input signal circuit. The impedance is tuned to the control device during a fault-free state and is detunable upon detection of a fault so as to signal the detected fault to the control device via the input signal current circuit.

主权项

1. A safety-related communication system comprising:
a control device being configured to deliver digital activation and deactivation signals for controlling a load through an input signal current circuit and configured to discriminate between a fault-free state impedance and different fault state impedances detectable through the input signal current circuit; and a safety relay for connecting a power supply voltage to the load under the control of the control device, the safety relay including:
at least two signal inputs of the input signal current circuit connecting the safety relay to the control device;at least two load outputs of a load current circuit configured to connect the power supply voltage to the load,at least two activatable switching elements connected in parallel and configured to switch the load current circuit on or off based on an activation signal at the input signal current circuit;a diagnostic device configured to detect different faults in at least one of the load current circuit and the safety relay and to produce a fault state signal with respect to a detected fault; anda signaling device connected via a control logic to the diagnostic device for receiving a control signal indicating a fault-free state or a control signal indicating a fault state from the control logic and for providing the fault-free state impedance or the fault state impedance with respect to the detected fault at the input signal current circuit for being monitored by the control device and signaling any detected fault.