Baumer_GIM700DR_CANopen_EN_V1.00_MNL.docx
www.baumer.com
27.04.21
6/32
3.2
CANopen
Under the technical management of the Steinbeis Transfer Centre for Automation, the CANopen profile was
developed on the basis of the Layer 7 specification CAL (CAN Application Layer). In comparison with CAL,
CANopen only contains the functions suitable for this application. CANopen thus represents only a partial
function of CAL optimized for the application in hand, so permitting a simplified system structure and the use
of simplified devices. CANopen is optimized for fast data exchange in real time systems.
The organization CAN in Automation (CiA) is responsible for the applicable standards of the relevant profiles.
CANopen permits:
•
Simplified access to all device and communication parameters
•
Synchronization of several devices
•
Automatic configuration of the network
•
Cyclical and event-controlled process data communication
CANopen comprises four communication objects (COB) with different characteristics:
•
Process data objects for real time data (PDO)
•
Service data objects for parameter and program transmission (SDO)
•
Network management (NMT, Heartbeat)
•
Pre-defined objects (for synchronization, emergency message)
All device and communication parameters are subdivided into an object directory. An object directory encom-
passes the name of the object, data type, number of sub-indexes, structure of the parameters and the ad-
dress. According to CiA, this object directory is subdivided into three different parts. Communication profile,
device profile and a manufacturer-specific profile (see object directory).
3.3
CANopen communication
3.3.1
Communication profile
Communication between the network users and the Consumer (PC / Control) takes place by means of object
directories and objects. The objects are addressed via a 16-bit index. The CANopen communication profile
DS 301 standardizes the various communication objects. They are accordingly divided into several groups:
•
Process data objects PDO for real time transmission of process data
•
Service data objects SDO for read/write access to the object directory
•
Objects for synchronization and error display of CAN users:
SYNC object (synchronization object) for synchronization of network user
EMCY object (emergency object) for error display of a device or its peripherals
•
Network management NMT for initialization and network control
•
Layer Setting Services LSS for configuration by means of serial numbers, revision numbers
etc. in the middle of an existing network
3.3.2
CANopen message structure
The first part of a message is the COB-ID (identifier).
Structure of the 11-bit COB-ID:
Function code
Node-ID
4-bit function code
7-bit Node-ID
