CANopen Fundamentals

The CANopen Standard

The framework of this standard was developed as part of a project funded by the European Union. In 1995 the specifications that had been created up to that point were transferred to the organization CiA e.V. (CAN in Automation). Since then the standard has been maintained and further developed under the auspices of this CAN user organization. Since 2002 it has been available as a European standard (EN 50325-4 2002 Part 4: CANopen).

The CANopen standard describes the exchange of data in a CAN-based network. This standard defines both the fundamental communication mechanisms (communication profile) and the functionalities of communicating devices (device profile). This means that interpretation of process data that are transmitted over the bus are also defined under CANopen.

Object Directory

Every CANopen device makes internal data (process data, parameters) available on the bus via a defined interface, whereby these internal data are organized in an object directory. Entries in the object directory are accessed via a 16-bit index and supplemental 8-bit sub-index. The index range is subdivided into logical segments to organize the structure so that it easier to comprehend by users. The name of a device, for example, can be read from index 0x1008 (sub-Index 0).

Index (hex) Object
0000 not used
0001-025F Data Types
0260-0FFF Reserved for further use
1000-1FFF Communication Profile Area
2000-5FFF Manufacturer Specific Profile Area
6000-9FFF Standardized Device Profile Area
A000-AFFF Reserved for further use
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