It‘s protocol specific but generally speaking a communication fault is trigged when cyclic messages do not arrive from master station to drive’s main or auxiliary datasets on time.
Each fieldbus has a specific mechanism, which triggers a protocol specific timeout counter. The timeout value can usually be modified with a configuration file or set with a master station.
Possible reasons for communication fault are:
Disconnected or broken communication cable between the drive and the master, Faulted master station, Faulted network component, Grounding problem and interference, Incorrectly configured master station, Incorrectly configured drive or fieldbus interface, if a comms loss is detected then the drive will go into error "E10027" and stop according to STOPMODE.