Cause:
- The STO input signals were interrupted while driving. If the interruption was longer than the parameter "T_STO" in the "Monitoring" menu, the travel was also aborted. In the case of shorter interruptions there are no travel interruptions, but an error entry will be saved at the end of the travel.
Remedial action:
- check the safety circuit
- check the activation of the STO inputs
- check the supply voltage of the relays 
- check the control voltage of the STO signals