CANopen Summary & Description 

CANopen: The European CAN Bus

Origin: CAN in Automation, 1993

Based on CAN (Controller Area Network) technology, borrowed from the automotive industry, and the RS485 electrical specification.

Maximum Number of Nodes: 64

Connectors: Popular ‘Mini’ 18mm and ‘Micro’ 12mm waterproof quick-disconnect plugs and receptacles, and 9 pin D-shell.

Distance: 100M to 500M

Baudrate: 125, 250 500 and 1000 Kbits/sec

Maximum Message size: 8 bytes of data per node per message

Messaging formats: Polling, Strobing, Change-of-State, Cyclic, and others

Supporting Trade Organization: CAN In Automation, http://www.can-cia.de/

Typical Applications: Commonly found in motion control systems, assembly, welding and material handling machines. Single-cable wiring of multi-input sensor blocks, smart sensors, pneumatic valves, barcode readers, drives and operator interfaces. 

Advantages: Better suited for high-speed motion control and feedback loop closure than other CAN based networks. High reliability, efficient use of network bandwidth, power available on the network.

Disadvantages: Acceptance limited outside of Europe. Protocol is complex and somewhat involved from developers’ point of view. Same general limitations as other CAN based networks (limited bandwidth, limited message size and maximum network length).

CAN’s Capabilities

CANopen is a family of profiles based on CAN, a higher-layer protocol (application layer and communication profile) providing additional functionality such as standardized communication objects for process data, service data, network management, synchronization, time-stamping and emergency messages. CANopen was developed within the CAN in Automation (CiA) international users and manufacturers group, over 300 companies strong.

CANopen networks provide multi-master functionality and broadcast communication, because they are based on CAN. In CANopen there are different methods specified to achieve real-time communications. CANopen specifies also a pre-defined master/slave connection set to unburden the newcomer from the task of distributing identifiers as required in CAN data link layer solutions. One of the important functions is the fragmentation of data blocks larger than 8 bytes. The transport protocol uses confirmed services to guarantee that the communication profile layer correctly receives configuration data. The CANopen communication profile makes products from different vendors interoperable.

The general difference of CANopen to master/slave-oriented fieldbuses is the capability that each node can access the bus and communicate directly to each other node without any master. Because CANopen is based on CAN, the communication profile provides event-driven process data transmission, which reduces communication as much as possible. For motion control applications there is also synchronous operation (cyclic and acyclic).

Object Orientation

CANopen, DeviceNet and Smart Distributed System are all object-oriented and provide a similar functionality regarding the transmission of real-time data, configuration data, and network management information. However, DeviceNet and Smart Distributed System are more connection-oriented, and CANopen is more message-oriented. There are also some minor differences in the fragmentation of larger data blocks. The three mentioned CAN-based higher-layer protocols are supported by the CiA organization and specify also the behavior and functionality of standard devices such as I/O modules, drives etc. to achieve interchangeability of devices produced by different manufacturers.

Applications in Multiple Industries

Besides the use in machine control systems (e.g. textile, printing, packaging, injection molding and other applications), CANopen is implemented by robotics manufacturers and in medical equipment such as computer tomographs and X-ray apparatus. CANopen networks are also used in forklifts and cranes. Other applications are public transportation (passenger and driver information systems) and maritime electronics (ship control systems). But the main application area is decentralized machine control.

(Courtesy CAN In Automation).

Synergetic: CANopen Masters and Slaves in Many Formats:

PC Adapter Cards: We have PC/ISA, PC104, PCI, PCMCIA, STD32, CompactPCI* and VME* Masters and Slaves for CANopen. They use the same configuration tools, hardware and software interface as all of our other Fieldbus interfaces (DeviceNet, Profibus, Interbus, etc…).

*Call for availability

Embedded Master Modules: Our COMMUNICATOR modules are credit-card sized boards that you can design into your controller, PLC, operator interface or other device that you wish to convert to Fieldbus. The same dual port memory, software drivers and configuration tool as our PC card is used regardless of the bus.

COMMMUNICATORS require a custom user hardware design with the COM module mounted as a daughter board and the Fieldbus connector on your hardware board. All other Fieldbus components are on the COM module. After designed, all other COM modules can be plugged into the same socket.

Embedded Slave Modules: The ANYBUS CANopen module allows you to design instant ControlNet, DeviceNet, Profibus, Interbus, and other Fieldbus connectivity into your product in a matter of weeks. Now you don’t have to be a CANopen expert to manufacture a CANopen-compatible product.

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