
IL•1F CANopen DS301 | 3 Basics |
3.2Communication 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
3.2.1Object 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, 1603h for mapping in R_PDO4.
Index | Subindex | Object | Meaning |
1603h | 00h | Number of elements | Number of subindexes |
1603h | 01h | 1st mapped object | First object for mapping in |
|
| R_PDO4 | R_PDO4 |
1603h | 02h | 2nd mapped object | Second object for mapping |
|
| R_PDO4 | in R_PDO4 |
1603h | 03h | 3rd mapped object | Third object for mapping in |
|
| R_PDO4 | R_PDO4 |
Table 3.2 Examples of index and subindex entries
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Fieldbus interface | 19 |