Cause : Standard bus timeout (STD BUSTIMEOUT) comes when there is no communication to the FCM 300. The warning will only be active when parameter 514 has been set to another value than OFF. 

• If parameter 514 has been set to stop and trip, it will first give a warning and then ramp down until it trips, while giving an alarm.
• Check connections on the serial communication cable.
• Parameter 513 Bus time interval could possibly be increased.
• Check the operation of the communication equipment. Verify a proper installation based on EMC requirements