Protocol Overview
EtherCAT (Ethernet for Control Automation Technology) is a high-performance, real-time Ethernet protocol developed by Beckhoff. It processes data on-the-fly as Ethernet frames pass through each slave node, achieving sub-microsecond synchronization across hundreds of devices.
CANopen is a higher-layer protocol built on the CAN (Controller Area Network) bus. It provides standardized device profiles, emergency handling, and object dictionary-based configuration. CANopen is popular in mobile machinery, medical devices, and compact industrial systems.
Head-to-Head Comparison
| Dimension | EtherCAT | CANopen |
|---|---|---|
| Bandwidth | 100 Mbps (Ethernet) | 1 Mbps max (CAN 2.0B) |
| Cycle Time | Down to 100 µs | Typically 1–10 ms |
| Node Count | Up to 65,535 per segment | Up to 127 per bus |
| Topology | Line, tree, star (any Ethernet topology) | Bus (line only) |
| Cable Type | Standard Ethernet Cat5e/Cat6 | Shielded twisted pair (CAN bus) |
| Max Cable Length | 100m per segment | Up to 1000m at 50 kbps |
| Slave Hardware Cost | Medium (dedicated ESC chip required) | Low (simple CAN transceiver) |
| Synchronization | Distributed clocks (DC) — sub-µs jitter | SYNC object — ms-level |
| Best For | Motion control, servo drives, robotics, large I/O systems | Sensor networks, small distributed systems, mobile machinery |
When to Choose EtherCAT
EtherCAT is the optimal choice when your application demands:
- High-speed motion control: Multi-axis servo systems, CNC machines, and robotics requiring sub-ms cycle times
- Large node count: Systems with 20+ distributed I/O nodes or slave devices
- Deterministic synchronization: Applications needing µs-level synchronization between multiple axes (e.g., gantry systems, electronic gearing)
- High data throughput: Vision data, high-resolution encoder feedback, or complex process data
Our EtherCAT STM32F429BIT6 board provides a complete EtherCAT slave implementation with integrated CAN for mixed-protocol architectures.
When to Choose CANopen
CANopen remains the better choice for:
- Cost-sensitive small systems: Applications with fewer than 10 nodes where CAN hardware cost advantage matters
- Long cable runs: Installations needing 200m+ cable distances (CAN supports up to 1000m at lower baud rates)
- Existing CAN infrastructure: Systems already using CAN-based sensors or actuators
- Mobile machinery: Vehicles and outdoor equipment where CAN J1939/CANopen is the industry standard
Our STM32F407 and STM32F103ZE boards both support CAN/CANopen for these applications.
Hybrid Architectures
In many real-world installations, you don't have to choose just one. A common architecture uses EtherCAT for the high-speed backbone (master-to-drive communication) and CAN/CANopen for local sensor networks within individual machines or cells.
This approach leverages the strengths of both protocols: EtherCAT's speed for time-critical motion control, and CAN's simplicity and cost-effectiveness for distributed sensors and valve actuators.
For more on protocol selection within specific machine types, see our PLC Replacement by Protocol guide.