{HEAD ~ Each} of the EDUs, keypad controllers and {TAIL ~ CCIs} of the system is connected to a common communication bus 
of
{ HEAD ~ Each } of the EDUs , keypad controllers and { TAIL ~ CCIs } of the system is connected to a common communication bus
HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH