Cause : Synchronization unsuccessful comes when synchronization between the basic clock cycle, DRIVE-CLiQ clock cycle and application clock cycle was started and was not able to be successfully completed (e.g. after switch-on).

1. Remove the cause of a possible DRIVE-CLiQ fault.

2. Initiate a new synchronization, e.g. as follows:

- remove the PROFIBUS master and re-insert again.
- restart the PROFIBUS master.
- switch-off the Control Unit and switch-on again.
- carry out a Control Unit hardware reset (RESET button, p0972).
- carry out a parameter reset and download the saved parameters (p0009 = 30, p0976 = 2, 3)