Comm Loss

What does F81 mean?

Communication over the drive's RS-485 (DSI) port has ceased, meaning the drive is no longer able to send or receive data from connected serial devices. This can lead to loss of control or monitoring via the serial interface.

• Broken or loose wiring in the RS-485 communication cable (e.g., A/D+, B/D-, common terminals).
• Incorrect communication parameters configured in the drive (e.g., P9-36 DSI Address, P9-37 Baud Rate, P9-38 Parity).
• RS-485 master device (e.g., PLC, HMI) stopped communicating or has failed.
• Improper termination resistors on the RS-485 bus (e.g., missing termination on end devices, multiple terminations).
• Excessive electrical noise or ground loop issues on the RS-485 bus, corrupting data packets.

Click steps to track your progress.

1. 1

   Inspect the RS-485 wiring (D+, D-, Common) at the drive's DSI port and the master device for loose connections or damage.

2. 2

   Verify drive communication parameters (e.g., P9-36 DSI Address, P9-37 Baud Rate, P9-38 Parity) match the master device and network specifications.

3. 3

   Monitor the communication status LEDs on the drive (if available) for activity or error indications.

4. 4

   Using a multimeter, measure the resistance across D+ and D- terminals at the drive to verify proper termination (typically 120 ohms if terminated).

5. 5

   Temporarily disconnect other devices on the RS-485 bus to isolate communication issues to a specific device or wiring segment.