Latching

A latching function is available for the safe digital input. This function can be activated via a parameter using the "Assist CS.." parameterization tool. Latching prevents a safety subfunction activated via the safe digital input from being deactivated without user intervention via the change in input signals from the "0" state to the "1" state. Latching sets the process value of the safe digital input to logical "0" until an acknowledgment has occurred.

Unlatching can occur as follows:

• Via the "Acknowledge F-DI" bit in the safe process output data.

With active parameterization, the safe digital input remains 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:

• Error acknowledgment
• Muting