A Primer on Network Management with CANopen Protocols
CANopen is an object-based standard communication protocol that was originally developed for motor and motion control applications where multiple devices (or nodes) interact via a controller area network (CAN) bus. While CANopen remains most widely used for embedded systems that enable automation in industrial settings, other verticals such as healthcare, building automation, automotive, and more also use it, and it can be adapted to other data link and physical layer protocols such as EtherCAT®.
CANopen enables plug-and-play interoperability between system nodes to help achieve the connected factory of Industry 4.0. It is a higher layer protocol that, in the context of a 7-layer OSI model, implements the network layer and up. The protocol’s standard configuration methods simplify integration by allowing device profile configuration both before and after installation.
What’s in the CANopen Standard?
CANopen leverages a system’s CAN hardware to manage configurations, access, and communications between disparate devices, thus defining an application layer protocol that connects and coordinates nodes across the CAN. This enables network management, device diagnostics, and messaging between nodes via a basic transport layer that allows message segmentation and desegmentation.
To control other devices, the manager node must implement four features in its controlling software:
- Communication unit to implement messaging protocols with server nodes
- State machine for manager device starting and resetting
- Object dictionary containing complete parameters that describe the functions of each node
- Application, or actual device function that is carried out based on the first three features
Within the CANopen standard are an addressing scheme, various communication subprotocols, and an application layer, which is defined by the device profile. The CiA 301 specification that CAN released in automation contains all the basic CANopen device and communication profiles, which can be used as a foundation for other, more specialized devices, each according to their own CAN automation protocols (for example, CiA 401 for I/O modules; CiA 402 for motor and motion control applications).
CANopen Modules Simplified
The TMCL-IDE and as well as the TMCM-CANopen tool for all CANopen modules simplify the use of standard CiA-402 motion control modes, such as profile positioning, profile velocity, and homing modes, to ease design and shorten time to market. Graphical CANopen object monitoring is integrated to further simplify initial setup and fine-tuning of any CANopen module.
A Brief Introduction to CANopen
Learn the basics of CANopen with this introductory video covering key elements of the CANopen standard, such as the object dictionary, services, SDO, PDO, and manager/server nodes. This is a quick and dirty primer on the six core concepts of CANopen: communication models and protocols, device states, object dictionary, electronic data sheet, and standardized device profiles.