CAN seminar

The development of CAN began when more and more electronic devices were implemented into modern motor vehicles. Examples of such devices include engine management systems, active suspension, ABS, gear control, lighting control, air conditioning, airbags and central locking. All this means more safety and more comforts for the driver and of course a reduction of fuel consumption and exhaust emissions.

To improve the behavior of the vehicle even further, it was necessary for the different control systems to exchange information. This was usually done by discrete interconnection of the different systems. The requirement for information exchange has then grown to such an extent that a cable network with a length of up to several moles and many connectors was required. This produced throwing problems concerning material cost, production time and reliability. The solution to the problem was the connection of the control systems through a serial bus system. This bus had to fulfill some special requirements due to its usage in a vehicle.

With the use of CAN, point-to-point wiring is replaced by one serial bus connecting all control systems. This is accomplished by adding some CAN-specific hardware to each control unit that provides the "rules" or the protocol for transmitting and receiving information via the bus. CAN or Controller Area Network is an advanced serial bus system that efficiently supports distributed control systems, It was initially developed for the use in motor vehicles by Robert Bosch Gmbh, Germany, in the late 1980s, also holding the CAN license. CAN is most widely used in the automotive and industrial market segments. Typical applications for CAN are motor vehicles, utility vehicles, and industrial automation. Other applications are trains, medical equipment, building automation, household appliances, and office automation.

FEATURES OF CAN

" Multimaster Concept
" No node addressing, Message identifier specifies contents &priority
" Easy connection and disconnection of nodes
" Broadcast and Multicast capability
" Sophisticated Error detection
" NRZ Code + Bit Stuffing for Synchronization
" Bus access Via CSMA

MULTIMASTER CONCEPT

CAN is a multi-master bus with an open, linear structure with one logic bus line and equal nodes. The number of nodes is not limited by the protocol.

ADDRESSING NODES

In CAN protocol, the bus nodes do not have a specific address. Instead, the address information is contained in the identifiers of the transmitted messages, indicating the message content and the priority of the message.