Old text backup: SDO service in CANopen protocol

SDO is an abbreviation of Service data Object Interface (Obiect), as the name implies to provide service data access interface, service data is some real-time requirements are not high data, usually refers to node configuration parameters, so SDO is generally used to configure and obtain the configuration parameters of the node. Its priority is only higher than the heartbeat (Heartbeat).

Since SDO is called a service, there must be a service provider and user, the provider is the SDO server, the user is the SDO client, each node in the CANopen network has an SDO server, Because most objects in the object Dictionary of each node are accessed through SDO, the object dictionary is accessed and the requested service is provided with an SDO server, of course.

Both SDO request and response messages are 8-byte data, including the object Dictionary index, sub-index, SDO command, and data. Here to pay attention to our familiar with the Ethernet FTP, SDO upload and download just the opposite, FTP is from the client's point of view to understand the upload and download, SDO is from the perspective of the server to understand, from the server to obtain data from the object dictionary to read the operation is called upload, Writing data to the server means writing to the object dictionary is called downloading.

(As of 2007.1.31)

Old text backup: SDO service in CANopen protocol