Interlocking
A latching function is available for the safe digital inputs. This function can be activated via a parameter using the "Assist CS.." parameterization tool. Interlocking prevents a safety sub-function activated via the safe digital inputs from being deactivated without user intervention via the change in input signals from the "0" state to the "1" state. Interlocking sets the process value of the safe digital input to logical "0" until an acknowledgment has occurred.
Unlatching can occur as follows:
- Via a safe digital input that is parameterized as "Acknowledge latching safe digital input".
- Via a safe digital input that is parameterized as "Acknowledge latching safe digital input and error".
- Via the "Acknowledge F-DI" bit in the safe process output data.
The safe digital inputs with active parameterization remain at logical "0" after each activation of the safety option until an acknowledgment has been carried out.
Unlatching is performed by a 0 → 1 edge. If a permanent high signal is present on the F-DI to which the unlocking function has been assigned, this is indicated by a warning after 20 seconds. The safe digital inputs with active parameterization remain at logical "0" after each activation of the safety option until an acknowledgment has been carried out.
If one of the following functions is assigned to the safe digital input, the latching function of an F-DI must not be activated:
- Acknowledge faults
- Unlatch F-DI
- Unlatch F-DI and acknowledge faults
- Muting
- Test mode
