1 The use of a CAN bus system

1) The use of a CAN bus system in a car makes it possible to network electronic modules such as control units or intelligent sensors such the wheel angle sensor. 2) The abbreviation "CAN" means Controller Area Network. The CAN bus system provides the following advantages for the car as an overall system: -Data exchange between control units take place on a uniform platform. This platform is call a protocol. The CAN bus acts as a so-called data highway -System expansions are easier to implement in the form of optional extras. -The CAN bus is an open system which permits adaptation to various transmission media such as copper or optical fibre cables. - A cross-system diagnosis is possible across several control units.

- - - A uniform wiring design between the control units connected to a bus system. The number of necessary data lines is significantly lower. The type, scope and direction of the data to be transmitted makes no difference as long as the bus is not overloaded. Information is transmitted digitally. All information can be easily transmitted in a digital format and decoded by another control unit. The digital transmission method makes detection and correction of transmission errors possible.

� First step

Second step

Third step

Fourth step

Data transmission using the example of engine speed detection: transmission -display - The following example describes the complete process for exchanging engine speed information from detection through to display in the rev counter. It explains the chronological sequence of the data transmission process and the interaction between the CAN modules and the control units.

What does the can data transfer? It transfer the data protocol between the control modules at short intervals. It is subdivided into seven areas. The data protocol: Comprises a long string of bits. The number of bits in the data protocol depends on the size of the data field.

� gateways are infrastructure components with which complex network structures can be implemented. � access to CAN networks via other communication systems. In each case, the protocols of the connected bus systems are mapped to the other communication model.

� window, lighting and seat control only need low speeds. � while engine, cruise control and antilock brakes require high speeds. � Two or three CAN buses may be used in a vehicle; for example, a high-speed bus may be dedicated only for safety (air bags, seat belt tensioners, etc. ).