Hardware reference guide

CPU Modules
35013379 11/2011 157
Setting the slide switch to the middle position assigns remote terminal unit (RTU)
functionality to the port; the following comm parameters are set and cannot be
changed.
Setting the slide switch to the bottom position gives you the ability to assign comm
parameters to the port in software; the following parameters are valid.
Rear Panel Switches
Two rotary switches (see 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.
NOTE: The highest address that may be set with these switches is 64.
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.
RTU Comm Port Parameters
Baud 9,600
Parity Even
Data Bits 8
Stop Bits 1
Device Address Rear panel rotary switch setting
Valid Comm Port Parameters
Baud 19,200 1,200
9,600 600
7,200 300
4,800 150
3,600 134.5
2,400 110
2,000 75
1,800 50
Parity Enable/Disable
Odd/Even
Data Bits 7 / 8
Stop Bits 1 / 2
Device Address 1 ... 247