PU Leave Out

Parameter unit disconnection

Mitsubishi Electric · FR-E500 Inverter

What does PU Leave Out mean?

This fault stops the inverter output if communication between the inverter and the Parameter Unit (PU) is suspended due to disconnection or errors. This occurs when specific settings (e.g., '2', '3', '16', or '17') are configured in Pr. 75, or if the number of successive communication errors exceeds the permissible retries when Pr. 121 is set to '9999' for RS-485 communication.

Common Causes

  • Loose or disconnected connection of the PU to the inverter.
  • Incorrect setting of Pr. 75 (PU communication settings) or Pr. 121 (RS-485 communication retry count).
  • Physical damage to the PU cable or connector.
  • Communication interference or errors on the RS-485 bus.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure the PU is securely fitted into its connector on the inverter.

  2. 2

    Verify the setting of Pr. 75 (PU communication settings) and Pr. 121 (RS-485 communication retry count) to ensure they are appropriate for the desired communication method.

  3. 3

    Inspect the PU cable and connectors for any signs of damage or wear.

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Verified technical data. Last updated: March 2026

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Source: Mitsubishi Electric FR-E500 Inverter