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

Method for testing actuators arranged in the load circuit of an output circuit for switching the load circuit, the method comprising:

• providing a plurality of actuators (10, 101;
• 20, 201) 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
• assigning an auxiliary contact (10H;
• 20H) to each actuator (10, 101;
• 20, 201);
• wherein the auxiliary contacts are connected to the control and evaluation device by means of at least one readback circuit (RK, RK1, RK2), such that only for the deactivation of all of the actuators assigned to each readback circuit, a standby signal is detected by means of this readback circuit as a readback signal by the control and evaluation device, and
• wherein the control and evaluation device is parameterized in such a way that the control of actuators arranged in series in the load circuit comprises, for their activation, 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 at least this long.