Siemens SIMATIC S7-1500 System Manual page 265

Test and service functions
14.1 Test functions
Difference between modifying and forcing
The fundamental difference between the modifying and forcing functions consists in the
storage behavior:
● Modifying: Modifying of tags is an online function and is not stored in the CPU. You can
end modifying of tags in the watch table or force table or by terminating the online
connection.
● Forcing: A force job is written to the SIMATIC memory card and is retained after a
POWER OFF. You can only end the forcing of peripheral inputs and peripheral outputs in
the force table.
Testing with a PLC tag table
You can monitor the current data values of tags in the CPU directly in the PLC tag table. To
do so, open the PLC tag table and start the monitoring.
You can also copy PLC tags to a watch or force table and monitor, modify or force them
there.
Testing with a data block editor
The data block editor offers different options for monitoring and modifying tags. These
functions directly access the actual values of the tags in the online program. Actual values
are the current values of tags in the CPU work memory at any moment during program
execution. The following functions for monitoring and modifying are available in the database
editor.
● Monitor tags online
● Modify individual actual values
● Create a snapshot of the actual values
● Overwrite actual values with a snapshot
Note
Setting data values during commissioning
During plant commissioning, you often need to adjust data values to adapt the program to
local conditions. The declaration table for data blocks offers some functions for this purpose.
Testing with the LED flash test
In many online dialogs, you can perform an LED flash test. This feature is useful if you are
not sure which device in the hardware configuration corresponds to the device currently
selected in the software.
If you click on the "Flash LED" button in STEP 7 under Online & diagnostics (online access),
an LED flashes on the device currently selected. The RUN/STOP, ERROR, and MAINT
LEDs flash on the CPU. The LEDs flash until you cancel the flash test.
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SIMATIC Drive Controller
System Manual, 11/2019, A5E46600094-AA