AMT58x-CB CANopen®
19
6.7 SDO objects
SDO messages are used to set and read values from the object
dictionary of the encoder. These parameters are described in the
“Object dictionary” section.
4 bytes at the most are used for CAN data, other 4 bytes are used for
Command, Index and Sub-index fields. SDO messages are always
followed by confirmation. It follows that when Master sends a SDO
message to Slave, slave always sends a reply (and a warning,
should an error occur).
SDO structure:
IDENTIFIER
from 4 to 8 CAN data bytes
COB-ID(hex)
0 1 2 3 4 5 6 7
F.C
.
Node-ID Com
Index
Sub
Data
1byt
e
LSB MSB 1byte LSB
… … MSB
Com command
Index parameter
index
Sub parameter
sub-index
Data parameter
value
6.7.1 Command
The command byte contains the type of telegram transmitted to the
CAN network.
Three types of telegram are available:
Set: to send configuration parameters to a device;
Req: used by master to read data from a device;
Warnings: used by slave to send error messages to master (e.g.
Index does not exist
, …).
Comman
d
COB
COB type
Data length
22h Set M
S request
not spec.
23h Set M
S request
4 byte
2Bh Set M
S request
2 byte
2Fh Set M
S request
1 byte
60h Set
S
M confirmation
0 byte
40h Req M
S request
0 byte
42h Req S
M reply
not spec.
43h Req S
M reply
4 byte
4Bh Req S
M reply
2 byte
4Fh Req S
M reply
1 byte
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