The Continuous Press Speed Control feature for MODBUS requires specific handshaking of function coils between the PLC and the XL controller.

The initial customer complained that the controller was getting stuck in single stroke mode.

To complete a speed change the PLC must request to change the speed and wait for the controller to lock its self into single stroke mode and respond with permission. If the PLC does not complete the handshaking correctly the controller could have gotten stuck in Single Stroke mode.

The controller code was modified to UnLock single stroke mode if the PLC cancels a Press Speed change before all of the handshaking has completed.

It may not fix the customers actual problem but it makes the controller more forgiving and fault tolerant.