Feedback monitoring

Feedback monitoring compares the states of the switching request *Ctrl with the respective feedback contacts *Fbk. A distinction is made between static and dynamic errors during monitoring. The monitoring function is enabled using the variable MonEn by an operator (e.g. via OPC UA) or initially in the module.

A static error MonStatErr is triggered by a change in the feedback contact if the switching request remains unchanged after the monitoring time MonStatTi has elapsed. An example of this is a motor where the supply voltage fails.

A dynamic error MonDynErr is triggered by a change in the switching request without a resulting change in the feedback contact after the monitoring time MonDynTi has elapsed. This can be triggered, for example, by a contactor that remains “stuck”.

The monitoring times in which the respective faults are triggered can be set by the internal PLC logic. The variable MonSafePos is used to describe the behavior of the interface when an error occurs.

The states of *Ctrl and *Fbk are continuously monitored independently of MonEn, so that when monitoring is enabled at MonEn = TRUE, the correct monitoring time always begins. If *Ctrl and *Fbk are in the same state when the feature is activated, the timer will not start. If they are different, the corresponding timer is started based on the most recently detected edge.

Inputs

It is possible to change the value of the input variable MonEn during runtime; however, according to the MTP policy, this is not permitted because the value is changed via manual operation (e.g., via OPC UA).

Outputs