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SERIAL · BASICS

What Is RS-485?

RS-485 is a serial communication standard that sends data as a differential signal over a twisted pair. That makes it resistant to electrical noise and able to run long cables, up to about 1,200 m, with many devices sharing one bus. It is widely used for industrial control, Modbus RTU and PTZ camera control.

01

The Short Answer

RS-232, the older serial standard, connects just two devices over a short single-ended link. RS-485 measures the difference between two wires instead, so interference that hits both wires cancels out. That is why it survives long runs through factories, vehicles and outdoor installations where RS-232 would fail.

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    PTZ camera control Protocols such as Pelco-D and Pelco-P steer pan, tilt and zoom over RS-485.
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    Industrial automation Modbus RTU links PLCs, drives, meters and sensors on one bus.
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    Building systems Access control, HVAC and lighting controllers share long cable runs.
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    Vehicles and transport Displays, ticketing and on-board equipment talk to a central computer.
02

Why It Matters

Rugged computers often carry RS-485 on locking M12 connectors for exactly these jobs. Our object tracking case study uses RS-485 to steer a PTZ camera from an edge AI computer, and our M12 A-coded FAQ covers the connector usually used for serial.