Data Structure Of Sdo Request Message - Delta AS Series Operation Manual

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10.4
Sending SDO, NMT and Reading Emergency Message
through the Ladder Diagram
You can edit the request message mapping area to affect the transmission of SDO, NMT and Emergency
messages. The following table shows the corresponding relations between the request message mapping
area, response message mapping area, and PLC device.
PLC device
D25000-D25031
D24000-D24031
The CANopen master can only send one SDO, NMT, or Emergency request message to the same device at a
time. Clear the request message mapping area to zero when sending SDO, NMT, or Emergency request
message through the WPL program.

10.4.1 Data Structure of SDO Request Message

Sending SDO through the ladder diagram reads or writes the slave parameter.
1. The data format of the SDO request message:
PLC device
D25000
D25001
D25002
D25003
D25004
D25005
D25006
D25007 - D25031

ReqID: the request ID. Whenever an SDO request message is sent out, the message is given a ReqID
for CANopen master to identify. When reading/writing another SDO message, the original ID number
must be changed. In other words, reading/writing SDO is triggered by changing of the value of
"ReqID". The ReqID range is between 00–FF (Hex).

Size: the length of the message data. The counting starts from D6253 with a byte as the unit. When
reading, it is fixed to four and when writing, it is four plus the byte number of data types of index and
subindex and the maximum value is eight. But when writing, if the data type of the index and subindex
is word, the data length is six. The data length is file if the data type is byte.

Node ID: the node address for the target equipment on a CANopen network.

Type: 01 indicates the read access; 02 indicates the write access.
Mapping area
SDO request message, NMT service message and
Emergency request message
SDO response message and Emergency response message
ReqID
Reserved
Message Header
Type
High byte of main index
Reserved
Message Data
Datum 1
Datum 3
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Request message
High byte
Command (Fixed to 01)
Size
Node ID
Low byte of main index
Sub-index
Datum 0
Datum 2
Reserved
Mapping length
64 bytes
64 bytes
Low byte