Bus systems in the automobile

The components installed in modern automobiles have different requirements for the installed bus system. For example, the engine management area requires immediate data transmission; an air conditioner on the other hand must react within fractions of a second to changes of temperature in the passenger compartment. In the latter, significantly higher delay times could be accepted. Therefore, as a rule, several bus systems with differing characteristics are installed in an automobile.

The following diagram shows a simplified representation of the bus systems which are used in an Audi A8 (as of model year 2003):

• The CAN bus is available in variations having differing properties. Depending upon the speed at which it can transmit data, it is used in the drive and comfort areas and for diagnostics.
• The LIN bus is a bus system subordinate to the CAN bus and is used for the triggering of certain components.
• The MOST bus is an optical high speed bus and therefore suitable for transferring multimedia data in real-time speed.
• The Bluetooth radio link requires no wiring for short distances and is used for wireless transmission of speech signals.