The RS-422 Standard
The RS-422 standard introduced in the early 1970s defines a balanced (or differential) data communications interface using two separate wires for each signal. Due to the high noise immunity of the RS-422 standard, high data speeds and long distances can be achieved.
The RS-422 specification allows reliable serial data communications for:
1. Distances of up to 1200 metres
2. Data rates of up to 10 Mbps
Only one line driver is allowed on a line, and up to ten line receivers can be driven by it. Figure 3 illustrates RS-422.
Figure 3. RS-422 Connection