CANopen communication
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TR-Electronic GmbH 2007, All Rights Reserved
Printed in the Federal Republic of Germany
Page 152 of 260
TR - EMO - BA - DGB - 0013 - 00
05/16/2007
4.2.2.1.1 SDO message format
The maximum 8 byte long data range of a CAN message is configured by an SDO as follows:
CCD
Index
Subindex
Data
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
Table 3: SDO message
The
command code
(
CCD
) identifies whether the SDO request is of the read or write
type. With a write command, the number of bytes to be written are also encoded in the
CCD.
In the SDO response the CCD indicates whether the request was successful. In the
case of a read command, the CCD also provides information on the number of bytes
read:
CCD Meaning
Valid for
0x23 Write 4 bytes
SDO request
0x27 Write 3 bytes
SDO request
0x2B Write 2 bytes
SDO request
0x2F Write 1 byte
SDO request
0x60 Write successful
SDO response
0x80 Error
SDO
response
0x40 Read request
SDO request
0x43 4 bytes of data
SDO response to read request
0x47 3 bytes of data
SDO response to read request
0x4B 2 bytes of data
SDO response to read request
0x40 1 byte of data
SDO response to read request
Table 4: Command codes for SDO
In the case of an error (SDO response CCD = 0x80), the data range contains a
4-byte-error code, which provides information on the cause of the error. The meaning
of the error codes can be found in Table 32, page 252.
