PU Disconnection / RS-485 Communication Fault

What does E.PUE mean?

The inverter output is shut off because communication between the inverter and the Parameter Unit (PU) has been suspended, or RS-485 communication errors exceeded the retry count or check time. This occurs when Pr.75 has PU disconnection detection enabled, or if Pr.121 or Pr.122 settings for RS-485 communication are exceeded. It indicates a loss of control or monitoring via the PU/RS-485 link.

• Loose or disconnected Parameter Unit (PU) cable (RJ-45 type) from the inverter's front panel port.
• Damaged PU cable (e.g., broken wires, bent pins on RJ-45 connector) causing intermittent communication.
• RS-485 communication parameters (e.g., Pr.117 Function selection for communication, Pr.118 Communication speed) not matching the connected master device.
• Electromagnetic interference (EMI) disrupting the RS-485 communication line due to unshielded cables or improper routing.
• Faulty RS-485 transceiver chip on either the inverter's control board or the connected master device.

Click steps to track your progress.

1. 1

   1. Verify the Parameter Unit cable is securely connected to both the PU and the inverter's RJ-45 port.

2. 2

   2. Replace the PU cable with a known good, shielded cable to rule out cable damage.

3. 3

   3. Check and ensure Pr.117 (Function selection for communication) and Pr.118 (Communication speed) are correctly set for the RS-485 network.

4. 4

   4. Inspect RS-485 wiring for correct polarity (DA/DB), shielding, and proper termination resistors at both ends of the bus.

5. 5

   5. Use a different Parameter Unit or RS-485 master device to isolate whether the fault is with the inverter or the external device.