Advantages of CAN bus
1. Strong real-time data communication between network nodes
First, the CAN controller operates in multiple modes. Each node in the network can compete to send data to the bus using a lossless, bit-by-bit arbitration method based on bus access priority (depending on the message identifier). Furthermore, the CAN protocol eliminates station address encoding, replacing it with encoding of the communication data. This allows different nodes to receive the same data simultaneously. These characteristics result in strong real-time data communication between nodes in a CAN bus network and facilitate the formation of redundant structures, improving system reliability and flexibility. In contrast, RS-485 can only form a master-slave structure system, and communication can only be performed through master station polling, leading to poorer real-time performance and reliability.
2. Short development cycle
The CAN bus is connected to the physical bus through the two outputs, CANH and CANL, of the CAN transceiver interface chip 82C250. The CANH pin can only be in a high or floating state, and the CANL pin can only be in a low or floating state. This ensures that the phenomenon seen in RS-485 networks—where multiple nodes simultaneously send data to the bus due to a system error, causing a short circuit and damaging some nodes—is avoided.
Furthermore, CAN nodes have an automatic output shutdown function in case of severe errors, ensuring that the operation of other nodes on the bus is not affected, thus preventing a "deadlock" state on the bus caused by a problem with a single node, as is common in networks. Moreover, CAN's comprehensive communication protocol can be implemented by the CAN controller chip and its interface chip, greatly reducing system development difficulty and shortening the development cycle—features that RS-485, which only uses electrical protocols, cannot match.
3. Fieldbus technology has become an international standard.
Furthermore, compared to other fieldbuses, the CAN bus is an internationally standardized fieldbus with many advantages, including high communication speed, ease of implementation, and high cost-effectiveness. These are also important reasons why the CAN bus is widely used and has strong market competitiveness.
4. One of the most promising fieldbus technologies
CAN, or Controller Area Network, falls under the category of industrial fieldbuses. Compared to general communication buses, CAN bus offers superior reliability, real-time performance, and flexibility in data communication. Due to its excellent performance and unique design, CAN bus is gaining increasing attention.
Its application is most widespread in the automotive field. Some of the world's most famous car manufacturers, such as BENZ, BMW, PORSCHE, ROLLS-ROYCE and JAGUAR, have adopted CAN bus to realize data communication between the car's internal control system and various detection and actuators.
Meanwhile, due to the characteristics of the CAN bus itself, its application scope is no longer limited to the automotive industry, but has expanded to fields such as automatic control, aerospace, marine, process industry, machinery industry, textile machinery, agricultural machinery, robotics, CNC machine tools, medical devices and sensors.
CAN has become an international standard and is widely recognized as one of the most promising fieldbuses. Typical application protocols include: SAE J1939/ISO11783, CANOpen, CANaerospace, DeviceNet, and NMEA2000.
CAN bus characteristics
1. Complete the framing process of communication data.
2. Theoretically, the number of nodes in the network is unlimited.
3. Free communication can be achieved between nodes.
4. Simple structure
5. Transmission distance and rate
Difference between ordinary cable and CAN bus
CAN bus cables typically use twisted-pair shielded cables with a characteristic impedance of 120Ω. However, ordinary cables do not have a characteristic impedance requirement.
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