1. Technical principle: The CAN bus adopts the technical principle of distributed conflict detection and non-destructive bit timing, and communicates through the nodes on the bus sharing the transmission medium (such as twisted pair). EtherCAT is based on Ethernet technology, using the master-slave structure and the master broadcast method to achieve synchronous communication of multiple slave devices within an Ethernet frame.

2.Transmission speed: The transmission speed of CAN bus is generally from a few hundred kbps to several 1Mbps, which is suitable for medium and low-speed application scenarios. EtherCAT supports higher transmission speeds, usually reaching 100Mbps. Even relying on supplementary EtherCAT G technology, the transmission rate can reach 1000Mbit/s or higher, which is suitable for high-speed applications that require fast real-time communication.


3. Real-time and synchronization: EtherCAT can ensure real-time data transmission, and the data transmission only receives the safe time limit between two frames. The unique synchronization of EtherCAT can ensure that all nodes are triggered synchronously, and the jitter time of the synchronization signal is far less than 1us.

4.Data packet length limitation: EtherCAT breaks through the limitation on SDO packet length in the Can bus.


5. Addressing mode: EtherCAT can traverse multiple nodes in one transmission, and the master station addresses according to the address set for each slave station. Addressing methods can be divided into: broadcast addressing, auto-increment addressing, fixed-point addressing, and logical addressing. CAN node addressing methods can be divided into: physical addressing and broadcast addressing.

6.Topology: The commonly used CAN topology is bus type; EtherCAT supports almost all topologies: star, linear, tree, daisy chain, etc., and supports various communication media such as cables and optical fibers. It also supports The hot-swappable feature ensures the flexibility of connection between devices.

To sum up, in encoder applications, there are significant differences between CAN bus and EtherCAT in terms of technical principles, transmission speed, real-time performance and synchronization, data packet length restrictions and addressing methods, and topology structures. An appropriate communication protocol needs to be selected based on actual needs and scenarios.

Post time: Jan-31-2024