ProSoft Technology MVI71-GSC - Manual (Page 68)

MVI71-GSC ♦ PLC Platform Reference
Generic Serial Communication Module
Page 68 of 82 ProSoft Technology, Inc.
January 31, 2008
5.1.14 RS-422
5.1.15 RS-485
The RS-485 interface requires a single two or three wire cable. The Common
connection is optional and dependent on the RS-485 network. The cable required
for this interface is shown below:
RS-485 and RS-422 Tip
If communication in the RS-422/RS-485 mode does not work at first, despite all
attempts, try switching termination polarities. Some manufacturers interpret +/-
and A/B polarities differently.