CANOpen

CANopen is a communication protocol and device profile specification for embedded automation based on the Controller Area Network (CAN). Developed and maintained by CAN in Automation (CiA), it provides a robust, scalable framework for connecting devices in industrial environments, covering real-time I/O, control, and diagnostics. CANopen runs on the CAN physical layer (ISO 11898) and supports multi‑master networks.

At the core of CANopen is the object dictionary, a standardized map of all device parameters. Communication is organized into services such as Service Data Objects (SDO) for configuration and Process Data Objects (PDO) for real-time data exchange. Network management is handled through Network Management (NMT), heartbeats for device status, and Layer Setting Services (LSS) for configuring node IDs and baud rates. Optional features include SYNC for time alignment and EMCY for emergency signaling.

CANopen defines standard device profiles to promote interoperability among devices from different manufacturers. The most common profiles include DS301 (general CANopen), DS401 (device profile for I/O modules), and DS402 (drives and motion control). Electronic Data Sheets (EDS) describe a device’s capabilities and its object dictionary entries, aiding integration and configuration.

In operation, networks may be configured in a boot sequence through NMT, with devices moving from pre-operational to operational states. SDOs are used for initial setup, while PDOs carry cyclic or event-driven I/O data with low latency, enabling deterministic control.

Applications of CANopen span industrial automation, robotics, packaging, medical equipment, building automation, and mobile machinery. Since its inception in the early 1990s, CANopen has evolved as a family of CiA specifications and remains widely deployed and actively maintained.