Download PLC_2_Unity_Referenc..

Operating Modes
Processing on Cold Start for Modicon M340 PLCs
Cause of a Cold Start
The following table describes the different possible causes of a cold start.
Causes
Startup characteristics
Loading of an application
Cold start forced in STOP
Restore application from memory card,
when the application is different from the
one in internal RAM
Cold start forced in STOP or RUN mode as
defined in the configuration
Restore application from memory card, with
Unity Pro commands PLC →Project
backup →....
Cold start forced in STOP or RUN mode as
defined in the configuration
RESET button pressed on supply
Cold start forced in STOP or RUN mode as
defined in the configuration
RESET button pressed on supply less than
500ms after a power down
Cold start forced in STOP or RUN mode as
defined in the configuration
RESET button pressed on supply after a
processor error, except in the case of a
watchdog error
Cold start forced in STOP. The start in RUN
mode as defined in the configuration is not
taken into account
Initialization from Unity Pro
Forcing the system bit %S0
Start in STOP or in RUN (retaining the
operating mode in progress at downtime),
initialization only of application
Restoral after power supply outage with loss Cold start forced in STOP or RUN mode as
of context
defined in the configuration
CAUTION
LOSS OF DATA ON APPLICATION TRANSFER
Loading or transferring an application to the PLC typically involves initialization of
unlocated variables.
To save the located variables:
z Avoid the initialization of the %MWi by unchecking Initialize %MWi on cold start
in the configuration screen of the CPU.
It is necessary to assign a topological address to the data if the process requires
keeping the current values of the data when transferring the application.
Failure to follow these instructions can result in injury or equipment damage.
35006144 07/2011
125