Tele-Communication (Telecom) Terms Glossary and Dictionary
EIA-485, formerly known as RS-485 or RS485, is a physical layer electrical specification of a two-wire, half-duplex, multipoint serial connection. The standard specifies a differential form of signalling. The difference between the wires’ voltages is what conveys the data. One polarity of voltage indicates a logic 1 level, the reverse polarity indicates logic 0.