Comm Loss
Allen-Bradley · PowerFlex 4 Adjustable Frequency
What does F81 mean?
Communication has been lost with an adapter or the connected network. This can be due to intentional disconnection, issues with wiring, or failure of a port expander or adapter. The drive's response to this loss is configured by parameter A105 [CommLoss Action].
Common Causes
- No communication detected from the control system or supervisory PLC.
- Serial communication port failure or incorrect settings (baud rate, parity).
- Master control unit offline or malfunction.
- Timeout on communication protocol (P0-24).
Repair Steps & Checklist
Click steps to track your progress.
- 1
Verify the physical wiring integrity and connections to the drive's communication port (RS485/DSI) and any associated port expanders or adapters.
- 2
Check if the communication adapter was intentionally disconnected; if so, adjust parameter A105 [CommLoss Action] to a suitable non-fault setting (e.g., 'Coast to Stop', 'Stop', 'Continu Last').
- 3
Inspect communication cables and connectors for any signs of physical damage or improper termination.
- 4
Confirm that communication parameters such as A103 [CommData Rate], A104 [CommNode Addr], and A107 [CommFormat] are correctly configured for the network.