explaination of CANbus

can someone explain or refer me to anything that would help me understand "CANbus" ?????   i have an 2004 durango and keep hearing techs refer to this term....   need to upgrade my system but want to make sure i know whats going on first, THANK...." will85iroc "

The Controller Area Network (CAN) serial data line is high speed serial data bus used to communicate information between the Electronic Brake Control Module (EBCM), the Engine Control Module (ECM) and the Transmission Control Module (TCM). Typical data-transmission speeds must be high enough to ensure that the required real-time response is maintained.

The addressing scheme employed with CAN assigns a label to every message, with each message receiving a unique "identifier". The identifier classifies the content of the message (such as engine speed). Each module processes only those messages whose identifiers are stored in the module's acceptance list. This is CAN's form of message filtering.

The identifier labels both the data content and the priority of the message being sent. Each module can begin transmitting its most important data as soon as the bus is unoccupied. When more than one module starts to transmit simultaneously, the message with the highest priority is assigned first access. A module responds to failure to gain access to the bus by automatically switching to receive mode, that module then repeats the transmission attempt as soon as the bus is free again.

The Next Generation  of serial data may rest with CAN in something called a Local Area Network (LAN). The idea is to have a multiple speed bus of low, medium and fast. The low speed would be for items of driver input (Air Conditioning and Power options like windows and door locks). Medium speed for entertainment and comfort things like remote CD players and DVD players that are out now for 2002. High speed will be for real time items like desired torque and ABS. But this technology will be a while in coming.

Kevin Gerry

Certified Electronics Technician

MECP First Class Installer

Owner/Installer

Classic Car Audio

since 1979