What Does RS-485 Mean?

RS-485 is a multipoint communications standard set by the Electronics Industry Alliance (EIA) and Telecommunications Industry Association (TIA). RS-485 supports several connection types, including DB-9 and DB-37. Because of lower impedance receivers and drivers, RS-485 supports more nodes per line than RS-422.


RS-485 is also known as EIA-485 or TIA-485.

Techopedia Explains RS-485

RS-485 is effective in applications with significant electrical interference (noise) requiring a long transmission distance. Thus, the standard is often used in industrial applications. It is as an inexpensive local area network (LAN) connection that allows multiple receivers to connect within a multidrop configuration. RS-485 does not include a communications protocol.

Data transmission rates range from 35 Mbps (up to 33 feet)-100 Kbps (up to 4,000 feet). Because star and ring configurations are not recommended, equipment installed along RS-485 transmission lines (known as nodes, stations or devices) are connected as series. However, if necessary, star or ring configurations may be accommodated with special star/hub repeaters.

RS-485 uses a two-wire twisted pair bus. Although not always required, RS-485, like RS-422, may be configured with four wires as full-duplex. With certain restrictions, RS-422 and RS-485 may be co-configured.

Additionally, the RS-485 specification is used by Small Computer System Interface (SCSI)-2 and SCSI-3. RS-485 also may be used to allow remote connectivity between PCs and remote devices.


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Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…