CAN Vs CANopen
CAN (Controller Area Network) and CANopen are communication protocols commonly used in the field of automotive and industrial automation to facilitate communication between various devices and components within a system.
What is CAN (Controller Area Network)
• CAN is a robust and widely used communication protocol designed for real-time applications in
which devices need to communicate with each other over a shared bus.
• It was initially developed by Robert Bosch GmbH in the 1980s and has since found applications in
various industries beyond automotive, including industrial automation, aerospace, and more.
• CAN is a two-wire serial communication protocol that uses a differential signaling scheme to
transmit and receive data. It offers reliable communication even in noisy environments and is
resistant to electrical interference.
• CAN uses a message-based communication approach, where nodes on the network (devices or controllers)
send messages to each other. These messages can contain data, control commands, or other information.
• It is a multi-master protocol, meaning that any node on the network can transmit data, and collision
resolution is built into the protocol.
• CAN is characterized by its high data transfer rate, deterministic communication (consistent and predictable timing),
and error detection and correction mechanisms.
What is CANopen ?
• CANopen is a higher-level communication protocol and device profile specification that is built
on top of the CAN protocol.
• It standardizes the communication and application layer protocols for devices and systems that utilize
CAN as their physical layer.
• CANopen defines a set of communication services and objects, each with specific functionality.
These services and objects enable the seamless exchange of data and commands between devices on a CANopen network.
• CANopen is used extensively in industrial automation, machine control, and various other applications
where interoperability and standardization are crucial. It simplifies device integration and system development.
• CANopen allows for a wide range of devices to be interconnected within a network, including sensors,
actuators, motor controllers, and more. Each device adheres to a specific device profile, ensuring that they
understand and respond to the same set of messages and commands.
Difference between CAN and CANopen
This table highlights the fundamental differences between CAN and CANopen, with CAN providing the lower-level communication framework, while CANopen builds on top of CAN to standardize higher-level communication and device interoperability.
| Parameters | CAN | CANopen |
|---|---|---|
| Operating protocol layers | Layer-1 (Physical layer), Layer-2 (Data link layer) | Layer-7, Application layer |
| Communication type | Low level messaging protocol | Higher level device communication |
| Standardization | Defines the physical and data link layers only | Defines application and communication services on top of CAN |
| Purpose | Provides a robust and real time communication bus | Defines a set of device profiles and services for seamless device integration |
| Message types | Data frames and remote frames | Object dictionary, PDOs, SDOs etc. |
| Message format | Primarily consists of data and control bits | Consists of objects with data, indices and attributes |
| Interoperability | Devices need to follow CAN protocol for physical and data link layers | Devices adhere to specific CANopen device profiles for communication |
| References | ISO 11898-1, 11898-2, ISO 16845, ISO 16840 | CiA 303-1, 303-2, 303-3 |
| Device integration | Requires more custom configuration for each application | Simplifies device integration and ensures consistent communication between devices |
| Application | Used in various industries including automotive, aerospace, and industrial automation | Primarily used in industrial automation for device interoperability |
Conclusion : In summary, CAN is the underlying communication protocol that provides the physical and data link layers, while CANopen is a higher-level protocol that standardizes the way devices communicate over the CAN network. CANopen is particularly valuable in complex systems where various devices and components need to work together seamlessly, offering a standardized way to ensure interoperability.