A discrepancy alarm for the valve is also configured. The electric motor turning the valve may be damaged if the valve for some reason gets stuck and is still driven. An alarm indicating a discrepancy fault is therefore implemented. The alarm is turned on if the valve does not reach the correct limit switch in a predefined time.

In this excercise a discrepancy time of 10 seconds is used.

Note that the user can change the order for valve position while it is already moving:

1. Control switch is turned to Open (A) position
2. The valve starts to open
3. After nine seconds, the used turns the Control Switch to Closed (K) position. This happens before the valve has reached the Open Limit Switch
4. The valve starts to close
5. The valve reaches the Closed Limit Switch 18 seconds after it started moving
6. The discrepancy alarm must not be activated as it did not take ten seconds for the valve to move in one direction