The tunnel consists of the creation of a bidirectional bridge between the veronte units, that communicate to each other sharing information about an external device connected to the serial or digital port. Let’s consider an example to clarify this concept.
Imagine that we would like to have a button connected to the air autopilot to launch a parachute. It is not possible to physically connect the button because the air autopilot is in the flying platform, so we need a different option. Here is where the tunnel becomes very useful. We could connect the button trough the serial or digital port to the ground autopilot, and then with the tunnel send the signal to the air one. With this configuration it would be like if the button were physically connected to the aircraft.