Communication failure is one of the common malfunctions in frequency converter operation. For Oulu frequency converters, a communication fault is displayed as ERR/FU16 on the operation panel. The causes and troubleshooting methods for communication failure are as follows:

1. Abnormal host computer operation: Check the wiring of the host computer.

2. Faulty communication cable: Inspect the communication connection lines.

3. Incorrect communication expansion card P0-28 settings: Configure the correct communication expansion card type.

4. Incorrect Pd group communication parameter settings: Ensure proper configuration of communication parameters.

After performing the above checks, attempt to restore the frequency converter to factory settings.