ProSoft Technology MVI56-LTQ - Manual (Page 72)

Reference MVI56-LTQ ♦ ControlLogix Platform
User Manual Limitorque Valve Actuator Master Communication Module
Page 72 of 98 ProSoft Technology, Inc.
August 30, 2010
5.3.5 RS-485 Application Port(s)
The RS-485 interface requires a single two or three wire cable. The Common
connection is optional, depending on the RS-485 network devices used. The
cable required for this interface is shown below:
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.
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.
RS-485 and RS-422 Tip
5.3.6 DB9 to RJ45 Adaptor (Cable 14)