Hardware reference guide

CPU Modules
178
35013379 11/2011
Key Switch Description
The following table provides descriptions of the key switch information.
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.
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.
Key Switch Description
Key
Switch
Position
Controller Status Memory
Protected From
Programmer
Changes
Will Accept
Programmer
Stop or Start
Key Switch
Transition
Stop Controller is stopped
and disables
Programmer
changes.
Y N From Start or
Memory Protect:
Stops controller, if
running, and
disables
Programmer
changes
Mem Prt Controller may be
either stopped or
running and
Programmer
changes are
disabled. The user
cannot write to
unlocated variables.
Y N From Stop or Start:
Prevents
Programmer
changes, controller
run status is not
changed
Start Controller may be
either stopped or
running.
Programmer may
make changes and
start/stop the
controller
N Y From Stop: Enables
Programmer
changes, starts
controller.
From Memory
Protect: Enables
programmer
changes, starts
controller if stopped.