What is the different between RS-485 and RS-422?
RS-422 uses 2 wires for simplex transmission. RS-485 can use 2 wires for half duplex transmission. Full duplex systems are implemented using 4 wires. Both RS422 and RS485 can be used in multidrop configurations however precautions must be taken to prevent more than one transmitter being active on the same bus at once.