Cause : PU disconnection comes when the inverter output if communication between the inverter and PU is suspended, e.g. the operation panel and parameter unit is disconnected, when "2", "3", "16" or "17" was set in Pr. 75 Reset selection/disconnected PU detection/PU stop selection.

This function stops the inverter output when communication errors occurred consecutively for more than permissible number of retries when a value other than "9999" is set in Pr. 121 Number of PU communication retries during the RS-485 communication with the PU connector.

1. Check that the FR-DU07 or parameter unit (FR-PU04/FR-PU07) is fitted tightly.
2. Check the Pr. 75 setting.