DVP-ES2/EX2/EC5/SS2/SA2/SX2/SE&TP Operation Manual - Programming
7.4.1 Data Structure of SDO Request Message
Sending SDO through the ladder diagram can read or write the slave parameter.
The data format of the SDO request message:
PLC device
Message
Header
D6251 Reserved
Size
D6252 Type
Node ID
D6253
Message Data
High byte of main index Low byte of main index
D6254
Reserved Sub-index
D6255
Datum 1 Datum 0
D6256
Datum 3 Datum 2
D6257 ~ D6281 Reserved
Command: Fixed to “01”.
ReqID: The request ID. Whenever an SDO request message is sent out, the message will
be given a ReqID for CANopen master to identify. When reading/writing another SDO
message, the original ID number must be changed. In other words, to read/write SDO is
triggered by changing of the value of “ReqID”. ReqID range: 00 (Hex) ~ FF (Hex).
Size: The length of the message data. The counting starts from D6253 with byte as the unit.
When reading, it is fixed to 4 and when writing, it is 4 plus the byte number of data types of
index and subindex and the maximum value is 8. But when writing, if the data type of index
and subindex is word, the data length is 6 or it is 5 if byte.
Node ID: The node address of the target equipment on CANopen network.
Type: 01 indicates the read access; 02 indicates the write access.
The data format of the SDO response message:
PLC device
D6000
Message
Header
ResID
Status code
D6001
Reserved Size
D6002 Type
Node ID
D6003
Message Data
High byte of main index Low byte of main index
D6004
Reserved Sub-index
D6005
Datum 1 Datum 0
D6006
Datum 3 Datum 2
D6007 ~ D6031 Reserved
Status code:
The indication of the status code values in the response message:
No data transmission request
SDO message transmission succeeds.
SDO message is being transmitted.
Error: SDO transmission time-out
Error: Illegal command code
Error: the length of the transmitted data is illegal.
Error: the length of the response data is illegal.