{HEAD ~ External hardware} that connects to I/O devices such as sensors, motors, monitors, machines, etc. can be connected to the invention via {TAIL ~ I/O boards} that receives and transmit digital signals, representing control information, to the bus 
{ HEAD ~ External hardware } that connects to I / O devices such as sensors , motors , monitors , machines , etc . can be connected to the invention via { TAIL ~ I / O boards } that receives and transmit digital signals , representing control information , to the bus
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