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CANopen defines a standardized application for distributed industrial automation systems based on CAN. The CANopen profile family is based on a “Communication Profile,” which specifies the basic communication mechanisms and on a standardized form for describing the functionality of devices.

The most important device types such as digital and analog I/O modules, drives, operating devices, sensors, or programmable controllers are described by so-called “Device Profiles.” In the device profiles the functionality, parameters, and data of standard devices of the corresponding types are specified. Based on the standardized profiles, devices of different manufacturers can be accessed via the bus in exactly the same manner. Therefore devices of different manufacturers are interoperable and exchangeable.

The key element of the CANopen standard is the description of the device functionality by means of an “Object Dictionary” (OD). The object dictionary is divided into two sections. The first section contains general device information such as device identification, manufacturer name, and so on, as well as communication parameters. The second section describes the specific device functionality. A 16-bit index and an 8-bit subindex identify an entry (“object”) in the object dictionary. The entries in the object dictionary provide the standardized access to the “Application Objects” of a device, such as input and output signals, device parameters, device functions, or network variables.

You can describe the functionality and characteristics of a CANopen device by means of an “Electronic Data Sheet” (EDS) using an ASCII format. An EDS must be understood as a kind of template for describing all the data and features of device as accessible from the network. The actual device settings are described by the so-called “Device Configuration File” (DCF). The EDS and DCF can be provided in the form of a data file, which can be downloaded from the Internet or stored inside the device.