RS485 Home Page

RS485 is a serial communication protocol.
It is especially robust, and can be used for communication over long distances and in noisy environments.
The RS485 standard only specifies hardware. It does not say anything about the software or actual data protocol.
Further, there is no error checking or correction in the hardware. All such must be done in user's software.
Speed in bit/sec times distance in meters should be below 10⁸
So if you have a distance of say 20m, you can have bit rates up to 10 Mb/s.
(for 8-bit bytes, this translates to 1.2M baudrate)
Only two wires are needed between nodes. Twisted pair wires are commonly used.
In this mode, communication is simplex, ie. one-directional, ie. you cannot send and receive at the same time.
Full duplex systems can be built using 4-wires.

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