Simulate mode can be used to test a program on the PC without the controller and therefore does not require the program to be built and deployed. Simulate mode is more limited than Debug mode because no hardware is available to provide the input required by some control blocks (e.g. hardware, scheduler, Modbus etc.).
►To run Simulate:
▪Click the Simulate button. 
Or, in the menu bar click Debug > Start Simulating. Or, press the Ctrl + F5 key.
The steps described on page above in Debug Your Project can be used in Simulate Mode to override and modify parameters so that different values and behaviors can be observed in the program.