Description of CAN bus technology
After the introduction of Controlled area network–CAN bus technology by Robert Bosch at a SAE congress in 1986 at Detroit, the resulted could be noticed in vehicle wiring getting reduced up to 2Kms. Thus, the overall weight of the vehicle was reduced up to 50 Kgs. in a vehicle like BMW 850 coupe.
Controller Area Network serial bus system, called as CAN bus technology is designed to support multi-master access, while handling short messages up to 8 bytes. While this means that collusion gets resolved by priority, the system offers high degree of reliability also, by having 15 bit CRC for every message.
Since its introduction at Society of Automotive Engineers (SAE), there have been many further innovations in the CAN bus technology. While Intel developed CAN chip 82526 and Philips also developed semiconductor 82C200 as a CAN controller, there are about 20 chip manufacturers catering to this technology now. CAN technology being purely a data link layer implementation program, it became quite popular for use in various capital equipment like textile machinery, apart from its original use in passenger cars and other transport vehicles. However, this further gave rise to the need of having standards for these layer implementations and data exchange programs.
CAN Bus Standards organizations
* An international users and manufacturers’ group called CAN in automation (CIA)
* International organization for standardization (ISO) and other relevant standards.
CAN Bus Specifications—Standards
* ISO/DIS 11898-1 —Deals with Data link layer and physical signals of CAN system, for vehicles.
* ISO / DIS 11898-2 for high speed medium access unit for road vehicles with CAN technology.
* ISO / DIS 11898 -3 for low speed fault tolerant medium dependent interface, for transport vehicles using CAN bus technology.
* ISO / DIS 11898-4 for time trigger communication in road vehicles using CAN system.
Apart from the above, standardization like EN50325 have enabled application layers now to be used in different kinds of machine controls with the use of components like DeviceNet and CANopen. Both these are addressing different applications. While CANopen is useful for almost all kinds of machine controls, DeviceNet is used for maximizing the factory automation. All the software and devices as well as the components required for the CAN Bus technology have to satisfy and perform as per one of these standards, depending on the application that CAN bus technology is delivering.
While we shall continue providing more information on CAN bus technology, in the forthcoming entries here; readers may look at other topics to gain knowledge on varied subjects.