CAN bus leads in-vehicle network, CANopen attempts to open the door to applications

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CAN bus leads in-vehicle network, CANopen attempts to open the door to applications [Copy link]

In the field of automotive electronics, the vehicle buses that are closely related to vehicle power, chassis and body mainly include CAN, LIN and FlexRay. The CAN bus has become the mainstream of vehicle buses due to its advantages such as reliability, real-time and flexibility, and has gradually penetrated from mid-to-high-end cars and commercial vehicles to family cars of 50,000 to 60,000 yuan.

At the CAN technology seminar jointly organized by the international CAN standards organization CiA, the US Atmel company, the German IXXAT company and the China Single Chip Microcomputer Public Laboratory (BOL) recently, BOL director Lu Jingjian mentioned that the CAN bus currently accounts for 85% of the market share in automotive powertrains. After the world's major automobile manufacturers produce cars that meet Euro III/Euro IV emission standards in 2008, more than 95% of the cars will use the CAN bus.

CAN bus is a multi-master bus. The communication medium can be twisted pair, coaxial cable or optical fiber. It is divided into high-speed CAN (250kbps-1Mbps) and low-speed CAN (10kbps-125kbps) buses. The former has many fault-tolerant functions.

, which is generally used in body electronic control; while the latter is mostly used in the electronic control of automobile chassis and engines.

From the perspective of the development of China's automotive bus, the independently developed technology based on the CAN bus has been successfully applied to new energy vehicles and traditional vehicles. Dr. Tang Xiaoquan from the Automotive Electronics Technology Application Research Group of the Institute of the Chinese Academy of Sciences introduced: "The research on automotive bus technology is divided into two stages, namely the function realization stage and the performance improvement stage. At present, the first stage of work in China has been basically completed." However, Tang Xiaoquan also pointed out that the testing of domestic automotive CAN bus systems is still in its infancy and cannot meet the requirements of industrialization. He said: "The focus of this stage of work is to ensure the completeness of the automotive bus system, and that the automotive bus system can work stably in different climate environments, different electromagnetic environments, and unexpected conditions."

Lv Jingjian emphasized: "If we want to push CAN to a deeper level of application, we need to rely on various types of application layer protocols." In fact, many international organizations have launched nearly 40 application layer protocols based on the CAN bus for different application fields. The more famous application layer protocols include SAE J1939, CAL, CANopen, etc.

J1939 was proposed for truck and lorry applications and played an important role in the promotion of CAN. However, its modularity is poor and it can generally only be applied to specific fields. The CAN Application Layer (CAL) protocol launched by some European companies to extend the application areas of CAN is theoretically correct and can be put into industrial applications. However, as a necessary theoretical step of the solution, each user must design a new sub-protocol, so it has not been promoted.

The CANopen protocol was initially advocated by Bosch and later handed over to the CiA organization for maintenance and development. CANopen is a sub-protocol based on CAL, designed with object-oriented thinking, with good modularity and high adaptability, and can be applied to a large number of application fields through expansion. CANopen not only defines the application layer and communication sub-protocols, but also defines a large number of industry rules for programmable systems and different devices, interfaces, and application sub-protocols. CANopen devices developed in accordance with these industry rules can achieve interoperability between products of different companies. In addition, the CANopen protocol is license-free, and any organization or individual can develop equipment that supports the CANopen protocol without paying royalties, which is one of the important reasons for the rapid development of CANopen.

The CiA organization currently has 417 members. Its CEO Holger Zeltwanger is confident about the CANopen market. He said: "For CANopen to become a standardized system, it needs to have several characteristics: standard system design, interoperability of products from different manufacturers in the same network, reduced dependence on specific equipment manufacturers, use of standard communication software and development tools, and flexibility."

In addition, Zeltwanger also introduced that CANopen is currently radiating from the automotive industry to more fields, and has been widely used in public transportation systems, medical equipment, marine electronic equipment and building automation systems. However, it is understood that domestic research on CANopen is still in its infancy. Except for BOL, there are currently few research institutes conducting related work, and China's standard-setting work in this field is still in the exploratory stage.