Fieldbus communication fault

What does ALARM 34 mean?

The fieldbus on the communication option card is not working. This prevents remote control or monitoring of the frequency converter, potentially leading to a loss of process control.

• Loose or damaged fieldbus communication cable connection at the option card, bus coupler, or master controller.
• Incorrect fieldbus address setting (e.g., Parameter P8-50) or baud rate configuration (e.g., Parameter P8-51) on the frequency converter.
• Missing or improperly placed termination resistors on the fieldbus segment (e.g., PROFIBUS DP, Modbus RTU).
• Faulty fieldbus option card in the frequency converter, preventing proper data transmission or reception.
• Malfunction of the fieldbus master controller or another device on the network causing communication interruptions.

Click steps to track your progress.

1. 1

   1. Visually inspect and re-seat the fieldbus cable at both the frequency converter option card and the master controller/bus coupler.

2. 2

   2. Confirm fieldbus address (e.g., P8-50) and baud rate (e.g., P8-51) parameters match the network configuration.

3. 3

   3. Verify proper placement and resistance values of termination resistors on the fieldbus network ends (typically 120 ohms).

4. 4

   4. Use a fieldbus diagnostic tool to monitor network traffic, error rates, and identify specific communication issues.

5. 5

   5. Power cycle the frequency converter (main input power off for 5 minutes) and the fieldbus master to reset communication modules.

6. 6

   6. If available, swap the fieldbus option card with a known good spare to isolate hardware issues.