ProSoft Technology MVI56E-MCM/MCMXT - Manual (Page 143)

MVI56E-MCM ♦ ControlLogix Platform Reference
Modbus Communication Module User Manual
ProSoft Technology, Inc. Page 143 of 199
June 18, 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.
6.3.7 DB9 to RJ45 Adaptor (Cable 14)
6.4 MVI56E-MCM Database Definition
This section contains a listing of the internal database of the MVI56E-MCM
module. This information can be used to interface other devices to the data
contained in the module.
Register Range Modbus Low Modbus High Content Size
0 to 5999 40001 50000 User Data 10000
10000 to 10009 50001 50010 Backplane Configuration 10
10010 to 10039 50011 50040 Port 1 Setup 30
10040 to 10069 50041 50070 Port 2 Setup 30
10070 to 12669 50071 52670 Port 1 Commands 2600
12670 to 15269 52671 55270 Port 2 Commands 2600
15270 to 15359 55271 55350 Misc. Status Data 80