Siemens SIMATIC S7 F Manual page 140

Programming
Result: The "Safety Program – S7 Program" dialog box appears.
3. Select the "Password..." button and cancel the access rights for the safety
program. This means the password for the safety program will be requested
again in the case of operations such as the compilation or downloading of
changes to the Safety Program.
4. If safety mode is inactive, activate it (see "Activating Safety Mode").
5. Click the "Simulation..." button and, in response to the query that appears,
confirm that you want the F-Blocks to be replaced by the simulation blocks.
6. In the "Copy" dialog box that appears, confirm that individual objects are to be
overwritten with "Yes" or that all objects are to be overwritten with "All".
Result: The F-Blocks of the Safety Program are overwritten by simulation
blocks of the same name from the Failsafe Blocks: F-Simulation Blocks
library. "Inactive" is displayed in the text box under the button.
7. Activate the simulation by clicking the button for the simulation
toolbar of SIMATIC Manager or by choosing the Options > Simulate Modules
menu command. All the programming device functions, such as downloading,
module status, etc., are then processed by PLCSim instead of the real
modules.
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on the
Fail-Safe Systems
A5E00085588-03