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ErrorLib — Industrial Fault Code Library

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17

Control word time-out

Danfoss · VLT HVAC Basic FC 101

What does 17 mean?

The frequency converter has stopped receiving valid control word commands via its serial communication interface, leading to a timeout. This alarm is active when parameter 8-04 Control Timeout Function is not set to [0] Off. If configured to Stop and Trip, the drive will safely ramp down and then trip, indicating a loss of communication. Unresolved communication loss prevents external control of the drive.

Common Causes

  • Loss of communication link due to a disconnected, damaged, or broken serial communication cable (e.g., RS485, Ethernet).
  • The master controller (PLC/DCS) has stopped sending valid control words or has lost power.
  • Incorrect serial communication parameters (e.g., P8-00 Protocol, P8-01 Address, P8-02 Baud Rate) configured in the drive.
  • Faulty communication module or port on the drive's control card.
  • Network collision or excessive noise on the communication bus interfering with data transmission.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the physical connection of the serial communication cable (e.g., RS485 A/B, Ethernet RJ45) at both the drive and the master controller.

  2. 2

    Check drive parameters P8-00 (Protocol), P8-01 (Address), P8-02 (Baud Rate), and P8-03 (Parity) match the master controller settings.

  3. 3

    Monitor communication activity using LED indicators on the drive's communication port or the master controller's module.

  4. 4

    Temporarily disable the control word timeout function (set P8-04 Control Timeout Function to 'No function') for diagnostic purposes.

  5. 5

    Use a communication diagnostic tool (e.g., Modbus RTU scanner) to test direct communication with the drive's address.

Browse all codes in this manual (40)
Verified technical data. Last updated: April 2026

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Source: Danfoss VLT HVAC Basic FC 101
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