Each device is allocated {HEAD ~ a fixed time} at which its input and diagnosis data is transmitted as {TAIL ~ data frames} to the controller 200 
Each device is allocated { HEAD ~ a fixed time } at which its input and diagnosis data is transmitted as { TAIL ~ data frames } to the controller 200
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH