The CANopen protocol originated from the CAN protocol used in automotive communications and is popular in Europe. BECKOFF was the first company to integrate the CANopen protocol, primarily promoting BECKOFF control solutions in conjunction with other third-party peripherals such as I/O, servo drives, and frequency converters.
CANopen consists of master and slave stations. One master station can network with up to 127 slave stations. Stations communicate with each other via a one-to-one connection, forming a distributed control network. It generally does not support multi-master mode. Compared to pulse, Modbus, and other traditional protocols, its advantages are: 1. Long transmission distance, up to 1 kilometer; 2. High speed, up to 1 Mbit/s; 3. More controllable I/O with more stations; 4. In motion control applications, it saves significant labor and hardware costs compared to pulse-based systems; 5. For applications requiring a large number of axes, it reduces the number of pulse axis modules, resulting in a more cost-effective overall solution.
Figure 1 Pulse-type system scheme
Figure 2 Bus Scheme
Because of these advantages, a large number of products based on the CANopen protocol have emerged in recent years. PLC and motion controller/card manufacturers have integrated the CANopen protocol and launched various CANopen master and remote slave I/O devices; servo manufacturers have integrated the CANopen protocol and launched various CANopen slave servos; inverter manufacturers have integrated the CANopen protocol and launched various CANopen slave inverters; even stepper motor manufacturers have launched slave drivers based on the CANopen protocol. Examples include BECKOFF's CANopen PLC master/slave devices; a Taiwanese company's CANopen PLC master and inverter slave devices; a well-known American company's CANopen PLC master/slave devices; and of course, Leadshine Intelligent's SMC606 CANopen master and slave I/O devices, as well as the L6C series servo slave devices and DM3C series stepper slave devices based on the CANopen protocol. In short, Leadshine Intelligent can provide a full range of CANopen bus products, from master to slave, open-loop and closed-loop.
Figure 3 Leadshine Product Solution
Currently, the main applications of products based on the CANopen protocol include:
1. Applications in production lines with high axis count and I/O requirements;
2. Distributed site applications with long distances;
3. Single-machine multi-axis applications, such as electronic equipment;
4. Applications of multi-joint robots.
Of course, CANopen also has its limitations:
1. While a speed of 1 Mbit/s is faster than other protocols, it still has its distance requirements;
2. Although it is a provincial line, if one station is interrupted, the entire network will be interrupted;
3. The stability of most domestically produced products still does not meet customer requirements.
So how can we successfully implement a CANopen bus product solution? When selecting and applying it, we recommend:
1. When setting up a network, use shielded cables and connectors, or simply choose from manufacturers that specialize in industrial bus systems.
2. When there are many shafts, don't forget to select terminating resistors for the last shaft;
3. Try to select master and slave stations from the same company to facilitate debugging and maintenance.
For more information, please follow the official WeChat account of "Leica Intelligent".
