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SERIAL · BASICS

What Is RS-422?

RS-422 is a serial communication standard that sends data as a differential signal over twisted pairs, so it resists noise and can run up to about 1,200 m. One transmitter can drive up to ten receivers, and with separate pairs for sending and receiving it works full duplex. It suits long, point-to-point links in industrial plants.

01

The Short Answer

RS-422 was designed to extend serial links beyond the short reach of RS-232. Because it compares two wires rather than measuring against ground, interference cancels out. RS-485 builds on the same idea but allows many transmitters on one bus, which RS-422 does not.

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    Long cable runs Linking equipment across a plant or yard.
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    Noisy environments Near motors, drives and heavy machinery.
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    One-to-many broadcast A controller sending to several displays or devices.
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    Full-duplex links Simultaneous send and receive on separate pairs.
02

Why It Matters

Our RS-232 vs RS-485 FAQ compares all three standards, and the British Steel case study shows protocol-selectable RS-232/422/485 on rugged panel PCs. See our rugged panel PCs.