CANopen

CANopen
Name	CANopen
Introduced	1990s
Domain	Industrial automation, embedded systems, motion control, medical devices, automotive

CANopen is an application-layer and communication-profile specification for devices based on the Controller Area Network. It standardizes device communication, configuration, and interoperability across embedded controllers, sensors, actuators, and human-machine interfaces. The profile was developed and maintained by the international association for standardization and implementation in automation, providing guidance for manufacturers, integrators, and system designers working with fieldbuses and real-time control networks.

Overview

CANopen was developed in the 1990s by industry groups influenced by earlier fieldbus work and networks such as Controller Area Network and organizations like Bosch and the CAN in Automation association. The specification provides application-layer services atop a data-link layer defined by ISO 11898 and complements other industrial standards such as IEC 61158 and IEC 61800. Major contributors and adopters include companies and institutions from the automation, automotive, medical, and robotics sectors, with interoperability events and plugfests organized by trade associations and consortia like OPC Foundation partners and regional test houses. The scope covers device profiles, object dictionaries, network management, and standardized communication objects to enable modular system architectures used in manufacturing sites, research labs, and transportation projects.

Architecture and Protocol Stack

The protocol stack places the application layer and communication profiles above the CAN data-link and physical layers defined by ISO 11898. Key components interact with layers and services familiar to implementers of OSI model-like architectures and embedded RTOS platforms such as those from Wind River Systems and FreeRTOS vendors. CANopen defines mapping of Service Data Objects (SDOs), Process Data Objects (PDOs), Network Management (NMT) commands, and emergency messages to CAN frames. Implementations often interoperate with development environments and toolchains provided by vendors like ARM Limited, Microchip Technology, STMicroelectronics, and NXP Semiconductors. Conformance to CAN identifier allocation and bitrate negotiation links to hardware and transceiver specifications by suppliers such as Texas Instruments and Infineon Technologies.

Device Profiles and Object Dictionary

Device profiles describe standardized behavior for classes of devices—motion controllers, I/O modules, sensors, encoders, inverters—maintained as technical specifications and application notes by industry associations and working groups including CiA subgroups and national standards bodies. Each device exposes an object dictionary: a structured collection of entries indexed by 16-bit and 8-bit identifiers, mapping variables, parameters, and communication settings to accessible data objects. The object dictionary mirrors practices used in other profiles standardized by organizations like IEC and is integrated into tool ecosystems from vendors such as Beckhoff Automation, Siemens, and Schneider Electric. Profile examples include encoder profiles, brake profiles, and motion control profiles that reference measurement standards and test procedures from laboratories and institutes such as PTB and university research groups.

Communication Services and Network Management

CANopen defines several service types: SDOs for configuration and parameter access, PDOs for cyclic or event-driven real-time data, NMT for state transitions and supervision, heartbeat and node guarding for liveness detection, and emergency messages for fault reporting. These services are used in systems built around PLCs from manufacturers like Rockwell Automation and Mitsubishi Electric, motion controllers from Yaskawa and Kollmorgen, and embedded controllers in aerospace projects involving organizations such as ESA and national research centers. Network management and device identification mechanisms enable integration with commissioning tools and asset management systems developed by companies like National Instruments and software providers that produce protocol stacks and conformance suites. Safety-related extensions and functional safety integration reference standards and bodies such as ISO 26262 and IEC 61508 where relevant.

Implementation and Tools

A broad ecosystem of commercial and open-source stacks, diagnostic tools, and development kits supports adoption. Commercial suppliers include embedded software firms and industrial automation vendors that supply stacks, configurators, and certification services; prominent semiconductor companies provide reference designs and evaluation boards. Open-source implementations and utilities exist in repositories maintained by research groups and community projects, often interfacing with platforms from Linux Foundation initiatives and embedded frameworks like Zephyr Project. Diagnostic and commissioning tools range from vendor-specific GUIs to universal analyzers produced by companies such as Vector Informatik, Peak System Technik, and HMS Networks, while test labs and interoperability events are coordinated by associations including CiA and regional standards organizations.

Applications and Use Cases

CANopen is widely used in industrial automation sectors—factory automation, packaging machines, conveyor systems—and in mobile machinery, medical devices, maritime systems, and renewable-energy installations. System integrators and OEMs in industries represented by trade associations like VDMA and SME select profiles for modular machine lines, robotics cells, and distributed sensor networks in projects undertaken at research institutes and corporate R&D centers. Typical deployments interconnect drives from vendors such as SEW-EURODRIVE, encoders from Heidenhain, sensors from SICK, and HMIs from Beijer Electronics. Use cases include synchronized motion control in assembly lines, distributed I/O in process skids, and telemetry in off-highway vehicles, often combined with higher-level SCADA and MES solutions provided by companies like Schneider Electric and Honeywell International.

Category:Fieldbus protocols