ProSoft Technology MVI69E-LDM - Manual (Page 95)

MVI69E-LDM ♦ "C" Programmable Contents
Linux Application Development Module Developer's Manual
ProSoft Technology, Inc. Page 95 of 130
August 21, 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)