You can "get" any signal from the vehicle, ( E.G. zero speed, park brake on, park brake off, lights on, door open etc. ) and process these signals, ( eg. vehicle stopped, zero speed, park brake on, door open = put door step out ). The signal processing is nearly infinite, depending on I/O. capacity of unit. signals can also be fed back in to the vehicle CAN BUS , with respect to safety and running of vehicle etc., (eg. switch on turn indicators and side marker lights when reversing )I'm curious about this as well. I'm building my van and trying to determine if this is something I might need. It seems to only be required for turning on circuits given certain actions (door opening, etc).
It is a very versatile unit.