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ErrorLib — Industrial Fault Code Library

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COF

CANopen® Communication Interruption

Schneider Electric · Altivar Machine ATV320 Variable Speed Drive

What does COF mean?

Indicates an interruption in the CANopen® communication with the drive. This means the drive is no longer receiving commands or transmitting data via the CANopen® network, leading to a loss of control and operational status.

Common Causes

  • Open circuit or short circuit in the CANopen® bus cabling (CAN_H, CAN_L, CAN_GND lines).
  • Incorrect CANopen® node ID (e.g., Parameter P9-01) or baud rate (e.g., Parameter P9-02) settings configured on the drive.
  • Missing or incorrectly placed termination resistors (120 Ohm) at the physical ends of the CANopen® bus.
  • Faulty CANopen® interface on the drive's control board or a problem with the CANopen® master device.
  • Excessive electromagnetic interference (EMI) on the CANopen® bus lines causing data corruption or packet loss.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Inspect the CANopen® bus cable for physical damage, proper shielding, and secure connections at all nodes.

  2. 2

    2. Measure the resistance across the CAN_H and CAN_L lines at the bus ends with power OFF to confirm proper termination (should be approx. 60 Ohms with two terminators).

  3. 3

    3. Verify the drive's CANopen® node ID (e.g., Parameter P9-01) and baud rate (e.g., Parameter P9-02) match the network configuration.

  4. 4

    4. Check the status LEDs on the drive's CANopen® interface for error indications (e.g., Red LED for Bus Off status).

  5. 5

    5. Temporarily disconnect other devices from the CANopen® bus (one by one) to isolate the drive and re-evaluate communication.

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Verified technical data. Last updated: April 2026

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Source: Schneider Electric Altivar Machine ATV320 Variable Speed Drive
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