Baumuller b maXX 1000 - Page 180

Basic of CAN
Parameter manual b maXX
®
1000
Document no. 5.07004.03 Baumüller Nürnberg GmbH
180
of 208
B.3
n Message frame structure
The COB ID of the request SDO results from 600h + address, from the response SDOs from 580
hex
+
address. The data field of the CAN data message frame (byte 8) for an SDO is organized into three parts,
a command specify CS (1 byte), a multiplexor M (3 bytes) and the actual user data area D0 - D3 (4 bytes).
SDO message frame:
The multiplexor M consists of the 16- bit index of an object and the related 8-bit-wide Sub-index. With seg-
mented message frames, the user data area is expanded by the 3 bytes of the multiplexor, whereby 7
bytes of user data per message frame can be transmitted. The command specified CS classifies the var-
ious SDO types.
n Expedited transfer
Objects can be written or read, with their data comprised of a maximum of 4 bytes. Only two message
frames are required, a request and a response. All objects with the indices 1xxx
hex
, 2xxx
hex
and 6xxx
hex
can be addressed via expedited SDOs.
n Writing objects
With the bmaxx1000 CANopen interface, expedited transfer is used to write objects. A client SDO (mas-
ter) transmits a write request to the bmaxx1000 CANopen slave interface. This slave carries out the re-
quest and acknowledges this with the response.
Initiate SDO download:
Figure 70: Initiate SDO download protocol
COB ID DLC Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7
600
hex
+
address
08
hex
CS M M M D0 D1 D2 D3
580
hex
+
address
08
hex
CS M M M D0 D1 D2 D3