A1920 alarm in Siemens V70 Drive indicates Drive Bus receive setpoints after To. This means the network output data (setpoints) arrived too late within the synchronized communication clock cycle.
Cause: Output data of Drive Bus master (setpoints) received at the incorrect instant in time within the Drive Bus clock cycle.
Remedy:
- Check bus configuration.
- Check parameters for clock cycle synchronization (ensure To > Tdx).
Note: To: Time of setpoint acceptance, Tdx: Data exchange time.
