Hardware reference guide

CPU Modules
35013379 02 October 2007 183
Key Switch The key switch protects memory from programming changes while the controller is
in operation. The following figure shows the key switch.
The CPU43412A has 1435KByte of Flash EPROM memory, which can be used to
save the program and the initial values of variables. On power up, if you have a
program in flash memory, you can choose the desired operating mode using the
PLC MEM switch on the processor front panel. The 140CPU43412A has a key
switch with Run, Mem Prt, and Stop positions.
Note: The key switch positions shown next to the switch (above) are for reference
only and are marked on the module as indicated on the right.
Stop position The application in Flash is not transferred to internal RAM: warm
restart of the application.
Mem Prt position The application in Flash is not transferred to internal RAM: warm
restart of the application.
Start position The application in Flash is automatically transferred to internal
RAM when the PLC processor is powered up: cold restart of the
application.
Stop
Mem
Prt
Start
Stop
Mem
Prt
Start
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