ProSoft Technology MVI56E-LDM - Manual (Page 219)

ControlLogix Platform ♦ "C" Programmable Cable Connections
Linux Application Development Module Developer's Manual
ProSoft Technology, Inc. Page 213 of 264
March 12, 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.
6.4.1 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.
6.5 DB9 to RJ45 Adaptor (Cable 14)