This model shows the concept of triggered subsystems and what the different trigger types are. A triggered subsystem is executed for one time step only each time the trigger port transitions from false to true in a certain direction. The transition of the trigger port may occur when the direction of the transition is rising, falling or both rising and falling.
A rising transition occurs when the trigger signal transitions from zero or below to a positive value. A falling transition occurs when the trigger signal transitions from zero or above to a negative value.
After running the simulation, look closely at the top plot in the scope. This shows a sine wave, a waveform and the grounded value of zero. As the waveform transitions through zero, each of the subsystems is triggered appropriately. The output of each subsystem is equal to the current value of the sine wave at the time.
To help view exactly what is going on, you may want to turn the scope cross-hair on. You can do this by double clicking on the block that says Scope Crosshair. This will enable a set of cross-hairs on the scope so that s you move your mouse you can line corresponding values up across the plots.