Cause : Communication error 4 comes when incorrect communication command from upper unit or malfunction caused by interference. “Warning” occurs when Pr.09-02=0 and the motor drive keeps running. The drive resets automatically when receiving the correct function code.

The code CE4 indicates an "Illegal command" error with your Delta MS300 drive. This means the drive received a command that it doesn't understand or can't execute.

1. Check if the communication command is correct.
2. Check if the setting for Pr.09-02 is the same as the setting for the upper unit.
3. Check the cable and replace it if necessary.