Siemens SIMATIC ET 200SP System Manual page 226

Test functions and eliminating problems
13.1 Test functions
Testing with the force table
The following functions are available in the force table.
● Monitoring of tags
Using the force tables, you can display the current values of the individual tags of a user
program or a CPU on the programming device or PC. You can monitor the table with or
without a trigger condition.
You can monitor the following tags:
– Bit memory
– Contents of data blocks
– Peripheral inputs (e.g. %I0.0:P)
● Forcing of peripheral inputs and peripheral outputs
You can force individual peripheral inputs or peripheral outputs.
– Peripheral inputs: Forcing of peripheral inputs (for example %I0.0:P) represents the
– Peripheral outputs: Forcing of peripheral outputs (for example %Q0.0:P) represents
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 by disconnecting 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 the LED flash test
In many online dialogs, you can perform an LED flash test. This function is useful, for
example, when you are not sure which device in the hardware configuration corresponds to
the device currently selected in the software.
When you click the "Flash LED" button, an LED flashes on the currently selected device. On
the CPU, the following LEDs flash: RUN/STOP LED, ERROR LED and MAINT LED. The
LEDs continue to flash until you terminate the flash test.
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"bypassing" of sensors/inputs by specifying fixed values to the program. Instead of the
actual input value (via process image or via direct access) the program receives the
force value.
the "bypassing" of the complete program by setting fixed values for the actuators.
Distributed I/O system
System Manual, 12/2015, A5E03576849-AF