rs485 and 485 communication, wiring method: rs-485 adopts half duplex working mode, support multi-point data communication. rs-485 bus network topology generally adopts the terminal matching bus structure. That is, a bus is used to connect each node in series, and ring or star networks are not supported. If you need to use a star structure, you must use a 485 repeater or 485 hub. rs-485 bus generally supports a maximum of 32 nodes, if the use of special 485 chip, can reach 128 or 256 nodes, the maximum can support up to 400 nodes.