Hardware reference guide

CPU Modules
35013379 02 October 2007 197
Rear Panel
Switches
Two rotary switches (refer to the following illustration and table) are located on the
rear panel of the CPU. They are used for setting Modbus Plus node and Modbus
port addresses.
SW1 (the top switch) sets the upper digit (tens) of the address; SW2 (the bottom
switch) sets the lower digit (ones) of the address. The illustration below shows the
correct setting for an example address of 11.
The following figure shows SW1 and SW2.
The following table shows the SW1 and SW2 address settings.
Modbus Port
Modem Support
Modbus Port 1 has full modem interfacing ability. Modbus Port 2 RTS/CTS
connections function properly for normal non-modem communications but do not
support modems.
Note: The highest address that may be set with these switches is 64.
Node Address SW1 SW2
1 ... 9 0 1 ... 9
10 ... 19 1 0 ... 9
20 ... 29 2 0 ... 9
30 ... 39 3 0 ... 9
40 ... 49 4 0 ... 9
50 ... 59 5 0 ... 9
60 ... 64 6 0 ... 4
Note: If "0" or an address greater than 64 is selected, the Modbus + LED will be
"on" steady, to indicate the selection of an invalid address.
1
3
0
9
2
6
4
5
8
7
1
3
0
9
2
6
4
5
8
7
SW1 (TOP)
SW2 (BOTTOM)
This document provided by Barr-Thorp Electric Co., Inc. 800-473-9123 www.barr-thorp.com