IEBus (Inter Equipment Bus) is a two wire bus used in the automotive industry as a communications bus between various devices (usually multimedia devices) by using half duplex asynchronous (multi-master) communication with CSMA/CD (Carrier Sense Multiple Access/Collision Detection) for access control. It allows for up to fifty units on the bus over a maximum length of 50 meters. Two differential lines are used; Data+ / Data-, often labeled as Bus(+) Bus(-).