Danfoss · VLT AutomationDrive FC 301/302
No communication is detected from the control word source to the frequency converter. This warning is active only when parameter 8-04 Control Word Timeout Function is not set to [0] Off. If set to [5] Stop and trip, the drive will ramp down to a stop and issue an alarm.
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Verify the fieldbus communication status on the master controller (PLC/HMI) and ensure it is sending data packets or control words.
Inspect the fieldbus cable for proper connection, damage, and correct termination resistors at both ends of the segment.
Check parameter 8-04 (Control Word Timeout Function) and 8-05 (Control Word Timeout Time) settings; adjust timeout time (e.g., increase from 1.5s to 3s) if network latency is high.
Monitor the status of the fieldbus option card LEDs (e.g., green/red) for communication activity and errors.
Perform a network diagnostic test (e.g., ping for Ethernet/IP, bus status for Profibus) from a connected device to verify connectivity.