| Introduction to Controller Area Network (CAN Bus) |
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| Written by Parthiban Kesavan | |
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Controller Area Network (CAN) is a network protocol which allows multiple nodes in a system to communicate efficiently with each other. It is a serial communication bus for real time applications which operates at a data rate of 1Megabits per second. CAN is event triggered and not time triggered and is more suitable for a periodic communication. Communication through CAN is very reliable and robust, thus used in noisy environments.
CAN is widely used for Automotive Applications to replace the complex wiring problems. Nowadays CAN bus is used for in-car electronics, aerospace, ships, medical electronics and also in Textile machineries. History of Controller Area Network Robert Bosch introduced CAN to be used in Automotive Application in order to reduce the complex wiring problems inside passenger cars. Most of the cars which are manufactured since 1980’s uses CAN as a standard for in vehicle communication. CAN is documented as an International standard as ISO11898 for high speed applications and ISO11519 for low speed applications. To discuss the growth of CAN several user groups have been formed. One of the first is CAN in Automation (CiA). Now in its 20th year CAN is still enhanced. In the future CAN would be used in every type of embedded systems and machines. OSI Model The Open System Interconnection Model is a reference to how messages are transferred in a network. All the communication protocols including CAN follows this standard. When a message is transmitted through a communication network, it is being processed by all the seven Layers of the OSI model. The top layer is the Software or Hardware Application which is trying to send the message through the network. The seven layers in the OSI model is shown in the following figure.  CAN Bus OSI MOdel CAN and the OSI Model
Many communication bus protocols do not use all the seven layers of this OSI Model. Since CAN is a closed network it doesn’t need to have security and to present the data in a user interface. Also it does not need to maintain sessions and logins. Hence it uses only two Layers such as Physical and Data Link Layer. The CAN OSI model shown in figure 1.1 explains the transfer of data between two nodes.  Two Layers of CAN |