5.2 RS-422/485 Circuitry
The RS-422/485 side of the Converter is made up of the driver, receiver, and line- termination networks. As described in Chapter 3, you can use switch S2 to either connect the receiver’s termination network to the line (terminate the RS-422/485 port) or leave it unconnected (unterminated).
Having the line terminated will reduce distortion and improve the overall signal quality in most applications. For point-to-point systems where only two devices are connected to the line, each device should have the termination network connected to the line. In multipoint applications, only the two devices at the extreme ends of the line should have the termination network connected to the line. If any of the other converters were configured as “terminated,” the amount of signal distortion would increase and probably cause errors in the data being transmitted. For more on the RS-422/485 connector pinning, see the Appendix.
