MVI56E-MCM ♦ ControlLogix Platform Reference
Modbus Communication Module User Manual
ProSoft Technology, Inc. Page 149 of 209
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.
6.3.7 DB9 to RJ45 Adaptor (Cable 14)
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