ProSoft Technology MVI69L-MBS - Manual (Page 148)

Reference MVI69L-MBS ♦ CompactLogix Platform
User Manual Communication Module
Page 148 of 154 ProSoft Technology, Inc.
January 6, 2014
Note: Terminating resistors are generally not required on the RS-485 network, unless you are
experiencing communication problems that can be attributed to signal echoes or reflections. In
these cases, installing a 120-ohm terminating resistor between pins 1 and 8 on the module
connector end of the RS-485 line may improve communication quality.
RS-485 and RS-422 Tip
If communication in the RS-422 or RS-485 mode does not work at first, despite
all attempts, try switching termination polarities. Some manufacturers interpret +
and -, or A and B, polarities differently.
7.6.4 DB9 to RJ45 Adaptor (Cable 14)