IEBus (Inter Equipment Bus) is a communication bus specification "between equipments within a vehicle or a chassis" of Renesas Electronics. It defines OSI model layer 1 and layer 2 specification. IEBus is mainly used for car audio and car navigations, which established de facto standard in Japan, though SAE J1850 is major in United States.IEBus is also used in some vending machines, which major customer is Fuji Electric.Each button on the vending machine has an IEBus ID, i.e. has a controller.Detailed specification is disclosed to licensees only, but protocol analyzers are provided from some test equipment vendors.Its modulation method is PWM (Pulse-Width Modulation) with 6.00 MHz base clock originally, but most of automotive customers use 6.291 MHz, and physical layer is a pair of differe