Delta DVP-ES3 Series

DVP-ES3/EX3/SV3/SX3 Series Hardware and Operation Manual
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2. SDO (service data object)
 The SDO builds the client/server relation between two CANopen devices. The client device can read
the data from the object dictionary on the server device and write the data into the object dictionary on
the server device. The SDO visit mode is “client/server” mode. The mode which is visited is the SDO
server. Every CANopen device has at least one service data object that provides the visit channel for
the object dictionary of the device. SDO can read all the objects in the object dictionary, and write all
objects into the object dictionary.
 The SDO message contains the index and subindex information used to position the objects in the
object dictionary, and the composite data structure can easily be passed by the SDO visit. After the
SDO client sends the reading/writing request, the SDO server replies. The client and the server can
stop SDO transmission. The requested message and the reply message are separated by different
COB-IDs.
 The SDO can transmit the data in any length. If the data length is more than 4 bytes, the data must be
transmitted by segment. The last segment of the data contains an end flag.
 The following table shows the structures of the SDO requested message and reply message.
The format of the requested message:
COB-ID
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
600 (Hex)
+Node-ID
Requested
code
Object index
Object
subindex
Requested data
LSB
MSB
bit7-0
bit15-8
bit23-16
bit31-24
The definition of the requested code in the requested message:
Request code (Hex)
Description
23 Writing 4-byte data
2B
Writing 2-byte data
2F
Writing 1-byte data
40
Reading data
80
Stopping the current SDO function
The format of the reply message:
COB-ID
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
580(Hex)
+Node-ID
Reply
code
Object index
Object
subindex
Reply data
LSB
MSB
bit7-0
bit15-8
bit23-16
bit31-24
The definition of the reply code in the reply message:
Reply code (Hex)
Description
43
Reading 4-byte data
4B Reading 2-byte data
4F
Reading 1-byte data
60
Writing 1/2/4-byte data
80
Stopping the current SDO function