SMAL CANlift
MAN SMAL I6 E 1.3.doc
Pag.12
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6.7 SDO objects
SDOs messages are used to read or modify Slave parameters. These parameters
are described in the “Object dictionary”.
Max 4 bytes are used for CAN data, other 4 bytes are used for Command, Index
and Sub;index fields. SDOs are always followed by confirmation.
When the Master sends a SDO to a Slave, it always replies (with Warning in case
of error).
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
1 byte LSB
MSB 1 byte 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 on 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 the Master (e.g. index
does not exist, …).
Command
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
41h
Req
S
M reply segmented SDO
80h
Warning
S
M reply
4 byte
