Communication Loss

What does F81 mean?

This fault indicates a loss of communication with the drive's control source, possibly due to an adapter disconnection, wiring issue, or a communication timeout. This fault's action (fault, stop, continue) can be configured by A105.

• Physical disconnection or damage to the communication wiring between the drive and its control source (e.g., I/O adapter, PLC).
• Incorrect communication timeout settings in the drive (e.g., P35-02 [Comm Loss Time]), leading to premature faulting.
• Control source (PLC/controller) failure or software logic halting communication with the drive.
• Faulty communication module or adapter in the drive, causing intermittent or complete loss of data exchange.
• High electrical noise or EMI interfering with communication signals on the control wiring.

Click steps to track your progress.

1. 1

   Inspect all communication cables and connectors between the drive and its control source for secure connections and physical damage.

2. 2

   Verify the drive's communication adapter status LEDs to confirm proper module operation and link integrity.

3. 3

   Check the P35-02 [Comm Loss Time] parameter; increase its value if communication interruptions are brief and transient (e.g., 5-10 seconds).

4. 4

   Confirm the control source (PLC/HMI) is active and sending commands to the drive by monitoring its output status or program logic.

5. 5

   Measure the communication signal integrity using an oscilloscope if possible, looking for noise or dropped packets. Ensure proper cable shielding and grounding.