Recommended Standard 422 (RS-422)

The standard for serial data communication protocol which specifies 4 wire, full duplex, differential line, multi-drop communications. It provides for balanced data transmission with unidirectional/non-reversible, terminated or non-terminated transmission lines. With a transmission rate of 9600 bps, RS-422 can be used at distances up to 4,000 feet (1,275 meters).