Car wiring diagrams: 4 Wire Rs485 Wiring Diagram, wiring diagram, wire wiring harness, schematic circuit diagram, wiring diagran, wireing diagram, wirring diagram, wiring daigram, wiring diagrams. First check the pinout connections and specifications of the devices you want to connect in order to Check the Data Sheet schematic or block diagram. The advantage of the wire connection is that all devices only see commands from the .Wires, set Switch up to ON for half duplex operation no echo . Switch down OFF=No. Termination, unless your serial baud rate is .Kbps or higher..RS and RS drive lines in a differential fashion two wires are required for each This requires wires one pair to Transmit and one pair to Receive..