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Shenyang Guangcheng Technology Co., Ltd.
CANopen bus coupler
—
GCAN-IO-8000
Product data sheet
Shenyang Guangcheng Technology CO.LTD.
NMT error control Network management error
control
1110b
701h-77Fh
B.
CANopen object dictionary (OD: Object Dictionary) is the core concept of CANopen
protocol. The so-called object dictionary is an ordered group of objects. Each object is
addressed with a 16-bit index value. This index value is usually called an index, and
its effective range is between 0x1000 and 0x9FFF. To allow access to a single element
in the data structure, an 8-bit index value is also defined. This index value is often
referred to as a sub-index. Each CANopen device has an object dictionary. The object
dictionary contains all the parameters describing the device and its network behavior.
The object dictionary usually records these parameters in an electronic data file (EDS:
Electronic Data Sheet), without the need to put these The parameters are recorded on
paper. For the master node in the CANopen network, there is no need to access every
object dictionary entry of the CANopen slave node.
The items in the CANopen object dictionary are described by a series of sub-protocols.
The sub-protocol describes each object in the object dictionary its function, name,
index, sub-index, data type, and whether this object is necessary, read and write
attributes, etc., so as to ensure the compatibility of devices of the same type from
different manufacturers. The core description sub-protocol of the CANopen protocol
is DS301, which includes the application layer and communication structure
description of the CANopen protocol. Other sub-protocols are supplements and
extensions to the description text of the DS301 protocol. The CANopen protocol
contains many sub-protocols, which are mainly divided into the following types.
1. Communication Profile
The communication sub-protocol describes the main form of the object dictionary and
the communication objects and parameters in the object dictionary. This sub-protocol
applies to all CANopen devices, and its index value ranges from 0x1000 to 0x1FFF.
2. Manufacturer-specific Profile
Manufacturer-defined sub-protocols. For special functions not defined in device
sub-protocols, manufacturers can define object dictionary objects in this area
according to requirements. Therefore, for different manufacturers, the definition of
object dictionary items with the same index may not be the same, and the index value
range is 0x2000~0x5FFF.
3. Device Profile
The device sub-protocol defines objects in the object dictionary for various types of
devices. At present, there are more than ten kinds of sub-protocols defined for
different types of devices, such as DS401, DS402, DS406, etc., and their index values
range from 0x6000 to 0x9FFF.
B.4 CANopen communication
The CANopen protocol mainly defines four objects: management message object
