5. Initial Programming
250
In case the CPU is initialized with an application already internally stored, it automatically goes to
Run Mode, without the need for a MasterTool IEC XE command.
Stop Mode
For CPU execution interruption, without losing the connection with the MasterTool IEC XE
software, the user must select the “Stop” option, available at the menu Debug, as shown on Figure
5-19.
Figure 5-19. Stopping the Application
In case the CPU is initialized without the stored application, it automatically goes to Stop Mode, as it
happens when a software exception occurs.
Writing and Forcing Variables
After Logging into a PLC, the user can write or force values to a variable of the project.
The writing command (Ctrl +F7) writes a value into a variable and this value could be overwritten by
instructions executed in the application.
Moreover, the forced writing command (F7) writes a value into a variable without allowing this value
to be changed until the forced variables be released.
It is important to highlight that, when used the MODBUS RTU Slave and the MODBUS Ethernet
Server, and the “Read-only” option from the configured relations is not selected, the forced writing
command (F7) must be done over the available variables in the monitoring window as the writing
command (Ctrl + F7) leaves the variables to be overwritten when new readings are done.
ATTENTION:
The variables forcing can be done in the CPU only in the Online mode.
Diagnostic variables cannot be forced, only written, because diagnostics are provided by the CPU
and must be overwritten by it.
When a forced writing is done into a redundant variable of the Active PLC, the MainTask execution
time will be impacted, in both Active and Stand-by PLC. This occurs because the two half-clusters
will exchange in each cycle information about the forced variables. Therefore, when forcing
variables in a redundant system, the user should consider the time added to the task execution time.
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General