Controller Area Network

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

CAN assigns a label to every message, with each message receiving a unique identifier. The identifier classifies content of message (i.e. engine speed). As a form of message filtering, each module processes only those messages whose identifiers are stored in module's acceptance list.

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