Device and method for actuator monitoring of a safety-related load circuit connected with two channels

Abstract

The invention relates to a method and to devices for monitoring actuators arranged in the load circuit of an output circuit for switching the load circuit, wherein a number of actuators (10, 101; 20, 201) are arranged in series in the load circuit, wherein each of the actuators is connected to a control and evaluation device (SA) by means of a separate control channel (SK1; SK2) for individual control, and an auxiliary contact (10H; 20H) is assigned to each actuator (10, 101; 20, 201), wherein the auxiliary contacts are connected via at least one readback circuit (RK, RK1, RK2) to the control and evaluation device in such a way that only when all of the actuators assigned to a readback circuit are deactivated, a standby signal is detected as a readback signal by the control and evaluation device by means of this readback circuit, and wherein the control and evaluation device is parameterized in such a way that, for their activation, the control of actuators arranged in series in the load circuit comprises the steps that, with reference to at least one readback circuit, initially only one actuator belonging to this readback circuit is always activated and the readback signal detected by means of the readback circuit assigned to this actuator is evaluated and at least one of all of the actuators arranged in series in the load circuit remains deactivated as long.

Dependencies are inferred from the claim text.