Siemens SIMATIC S7-1500 System Manual page 146

Testing with the force table
The following functions are available in the force table.
● Monitoring of tags
● Forcing of peripheral inputs and peripheral outputs
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
● Forcing: A force job is written to the SIMATIC memory card and is retained after a
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 station currently selected in the software.
When you click the "Flash LED" button, an LED flashes at the currently selected station. 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.
S7-1500 Automation System
System Manual, 02/2014, A5E03461182-AB
This allows the current values of the individual tags of a user program or a CPU to be
displayed on the programming device / PC or on the display of the CPU. Tags can be
monitored with or without a trigger frequency.
The following tags can be monitored:
– Bit memory
– Contents of data blocks
– Peripheral inputs (e.g. %I0.0:P)
You can force individual peripheral inputs or peripheral outputs.
– Peripheral inputs: Forcing of peripheral inputs (for example %I0.0:P) is a "bypassing"
of sensors / inputs by the specification of fixed values to the program. Instead of the
actual input value (via process image or via direct access) the program receives the
force value.
– Peripheral outputs: Forcing of peripheral outputs (for example %Q0.0:P) is a
"bypassing" of the complete program by the specification of fixed values to the
actuators.
end modifying of tags in the watch table or by disconnecting the online connection.
POWER OFF. An active force job is indicated in the display of the S7-1500 CPU through
a corresponding symbol. You can only end the forcing of peripheral inputs and peripheral
outputs in the force table.
Test functions and fault resolution
11.1 Test functions
145