When loading a Honeywell LM(Logic Manager), get UCN COMM ERROR (TDC 3000)

Doing the Prog. Load operation getting the PI from the HM and the DATA BASE from removable media, the error occurs prior to asking for the DATA BASE. The exact cause is unknown

Pull the LM battery and power down the LM rack to purge the LM memory. Insert the battery, power the rack back up and reload again. The LM should come to IDLE (with or without DATA depending on the existance of the checkpoint file)."