Hardware reference guide
CPU Modules
196
35013379 02 October 2007
Key Switch 
Description
The following table provides descriptions of the key switch information.
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.
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