The CAN bus (Controller Area Network) is a serial communication protocol bus for real-time applications that can use twisted-pair wires to transmit signals, and is one of the most widely used field buses in the world.The CAN protocol was developed by Robert Bosch in Germany for communication between a variety of different components in a car as a way to replace expensive and bulky distribution harnesses. The protocol's robustness has extended its use to other automation and industrial applications, and features include serial data communication with integrity, real-time support, transfer rates up to 1Mb/s, and 11-bit addressing and error-checking capabilities.
The CAN bus is a multi-master serial communication bus, and the basic design specification requires a high bit rate, high immunity to electrical interference, and the ability to detect any errors generated.The CAN bus can be used in automotive electrical control systems, elevator control systems, safety monitoring systems, medical instrumentation, textile machinery, and marine transportation, among other areas.
I. The characteristics of CAN bus:
1, has the advantages of real-time, long transmission distance, anti-electromagnetic interference, low cost;
2, using two-wire serial communication, error detection capability, can work in a high-noise interference environment;
3, with priority and arbitration functions, multiple control modules through the CAN controller CAN-bus, forming a multi-master local network;
4, according to the ID of the message can be decided to receive or block the message;
5, reliable error handling and error detection mechanism;
6, the information sent by the destruction of the message can be automatically re-transmitted;
7, nodes in the event of a serious error has the function of automatic exit bus;
8, nodes in the serious case of error, can work in a high-noise environment;
9, the bus has the function of automatic exit;
10, the node can be used for the communication between the two sides of the bus. /p>
8, the message does not contain the source address or destination address, only with flags to indicate the function information, priority information.
Second, the application of CAN bus
CAN bus in the networking and communication function of the advantages and its cost-effective according to determine it in many areas have broad application prospects and development potential. These applications have some **** the same thing: CAN is actually a bus topology in the field of computer LAN role. No matter what the occasion, it is the burden of any node between the real-time communication, but it has a simple structure, high speed, anti-interference, reliable, low price and other advantages. CAN bus was originally designed for the electronic control system of the car, the current production of automobiles in Europe in the application of CAN has been very common, not only that, this technology has been promoted to the train, ship and other means of transportation.
1, the application of automobile manufacturing
The application of CAN bus, can reduce the body wiring, further cost savings, due to the use of bus technology, signaling between the module requires only two signal lines. Wiring localization, the car in addition to the bus outside all the other lines across the body are no longer needed, saving the wiring cost. CAN bus system data stability and reliability, CAN bus has a line interference is small, anti-interference ability of the characteristics of a strong. CAN bus tailored for the automobile, fully taking into account the car on the harsh operating environment, such as ignition coil ignition generated by the powerful reverse charge voltage, eddy current The inrush current generated when the snubber is cut off and the high temperature of about 100℃ in the engine compartment of the car.
2, the application of large-scale instrumentation
Large-scale instrumentation is a reference to a certain number of steps on a variety of information collection, processing, control, output and other operations of the complex system. In the past, the electronic system of this kind of instrumentation often occupies a considerable part in terms of structure and cost, and the reliability is not high. After the adoption of CAN bus technology, there has been a marked improvement in this regard.
3, industrial control in the application
With the development of computer technology, communication technology and control technology, the traditional field of industrial control is experiencing an unprecedented change, and industrial control of the network, and more to expand the development of the field of industrial control space, bringing new opportunities for development. In a wide range of industrial fields, CAN bus can be used as a field device level communication bus, and compared with other buses, it has high reliability and performance-price ratio. This will be a major direction for the development and application of CAN technology.