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0198441113586, V2.01, 11.2008
IL•1F CANopen DS301 3 Basics
Fieldbus interface 19
3.2 Communication profile
CANopen manages communication between the network devices with
object dictionaries and objects. A network device can use process data
objects (PDO) and service data objects (SDO) to request the object data
from the object dictionary of another device and, if permissible, write
back modified values.
The following can be done by accessing the objects of the network de-
vices
• Exchange parameter values
• Start motion functions of individual CAN bus devices
• Request status information
3.2.1 Object dictionary
Each CANopen device manages an object dictionary which contains all
objects for communication.
Index, subindex The objects are addressed in the object dictionary via a 16 bit index.
One or more 8 bit subindex entries for each object specify individual data
fields in the object. Index and subindex are shown in hexadecimal nota-
tion with a subscript "
h
".
The following example shows the index entries and subindex entries for
the object receive PDO4 mapping, 1603
h
for mapping in R_PDO4.
Table 3.2 Examples of index and subindex entries
Index Subindex Object Meaning
1603
h
00
h
Number of elements Number of subindexes
1603
h
01
h
1st mapped object
R_PDO4
First object for mapping in
R_PDO4
1603
h
02
h
2nd mapped object
R_PDO4
Second object for mapping
in R_PDO4
1603
h
03
h
3rd mapped object
R_PDO4
Third object for mapping in
R_PDO4