Classic automotive technology is characterized by the direct coupling of mechanics and hydraulics with the vehicle functional units. As a rule, a mechanical movement of the driver, for example of the steering, clutch, accelerator or brake, is transferred mechanically or hydraulically to the functional unit. This mechanical/hydraulic coupling is dissolved by X-by-Wire technology and replaced by an electrical coupling. The steering movement is thus first converted into an electrical signal
, which is made available to the steering control unit as a control signal. X-by-Wire stands for "X" over wire, and the "X" can stand for any motor vehicle function: for gas-by-wire with the functions of the carburettor, injection, exhaust gas recirculation, or for power-by-wire with the functions of the starter, alternator, ignition, etc., or for shift-by-wire with the control functions for the manual gearbox, all-wheel drive and clutch, or in the case of drive-by-wire for the feedback information about the unevenness of the road
. X-by-Wire is a safety-critical world that migrates from mechanical-hydraulic coupling via mixed forms with electrical and electronic components to true X-by-Wire technology, which is implemented without mechanical coupling.
Since X-by-Wire technology involves time-critical applications, the FlexRayfieldbus is used to implement X-by-Wire applications.