IK360 -CAN
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Date: 23.01.2017 Page 17 of 41 Art.no. 86089 Mod. Status 10/17
5.5
Explicit Exchanges (SDO)
Service Data Objects (SDOs) allow a device's data to be accessed by using explicit requests.
The SDO service is available, when the device is in "Operational" or "Pre-Operational" state.
Types of SDO
There are two types of SDO:
Read SDOs (Download SDOs),
Write SDOs (Upload SDOs).
The
SDO protocol
is based on a 'Client / Server' model:
For a download SDO:
The server sends a request, indicating the object to be read. The client returns the data
contained within the object.
For an upload SDO:
The server sends a request, indicating the object to be written to and the desired value. After
the object has been updated, the client returns a confirmation message.
For an unprocessed SDO:
In both cases, if a SDO could not be processed, the device / master returns an error code.
A typical illustration of SDO for reading the current baud rate value explicitly is given below:
SDO passed as a new message to the device
We used a PEAK™ CAN master for this illustration. The PCAN®-USB adapter enables simple
connection to CAN networks.
The PCAN®-USB's compact plastic casing makes it suitable for mobile applications. It works as
a master on the CAN bus connection via D-Sub, 9-pin and in accordance with CiA 102
standards.
Object 3001h is to read the baud rate value from the IK360.
Transmit message
ID: 601h - Message to node number 1
Length: 8 byte
Data 0: Read (40h)
Data 1 & 2 : Object in big endian (30 01 is 01 30 in big endian format)
Data 3: Sub-Index (NA)
Data 4-7: Data to be written (NA in read command)