Virtual links are used to make models smaller, tidier and easy to maintain.
It also allows us to separate major functions that interact, but still shows us the interaction.
If for example we look at our sample crane model below, we can see that we have neatly separated the hoist braking system from the PLC which controls it, which is also nicely separated from the control system that sends inputs to the PLC.
Yet when we expand all these items, we can see the virtual links that create the continuity from the joystick right through to the hoist brake.