Control Word Timeout
Danfoss · VLT HVAC Drive FC 102
What does 17 mean?
The drive has not received a valid control word from the external controller (e.g., PLC via fieldbus) within the expected timeframe. This indicates a communication failure, causing the drive to stop or trip for safety reasons.
Common Causes
- Interruption or failure of the fieldbus communication link (e.g., disconnected cable, network switch fault).
- The fieldbus master controller (e.g., PLC) has stopped sending a valid control word within the configured timeout period.
- Incorrect fieldbus configuration parameters in the drive (e.g., P8-01, Fieldbus Address; P8-02, Baud Rate) or in the master.
- Drive parameter P8-10 (Control Word Timeout) is set to a value that is too short for the network latency or PLC cycle time.
- Faulty fieldbus option card in the drive preventing reception or processing of control words.
Repair Steps & Checklist
Click steps to track your progress.
- 1
1. Inspect the fieldbus communication cable (e.g., Ethernet, Profibus) for physical damage, loose connections, or incorrect shielding at both the drive and the master controller.
- 2
2. Verify the operational status of the fieldbus master (e.g., PLC), checking its diagnostic LEDs and internal diagnostic buffer for communication errors.
- 3
3. Confirm that all fieldbus parameters in the drive (e.g., P8-01, Fieldbus Address; P8-02, Baud Rate) precisely match the settings in the master controller.
- 4
4. Monitor the drive's fieldbus status (e.g., P8-03, Fieldbus Status Word) and confirm that control words are being received consistently from the master.
- 5
5. Increase the drive parameter P8-10 (Control Word Timeout) to a longer duration (e.g., 5-10 seconds) if transient network delays are suspected, after confirming network stability.