3 Basics | IL•1F CANopen DS301 |
Requesting process data One or more network devices with consumer function can request PDO messages from a producer. The producer is identified by the COB ID of the request and responds with the requested PDO.
| RTR |
|
1 | Producer | |
Consumer |
| |
0 | Daten |
Figure 3.18 Requesting a message with RTR = 1
The RTR bit (RTR: Remote Transmission Request) of a CAN message is used to detect a request. The COB ID remains the same for both mes- sages:RTR = 0: transmission of dataRTR = 1: request for data.
Setting RTR request You can set for each PDO separately whether it responds to RTR re- quests. This is switched on or off via subindex 01, bit 30h of each PDO. Subindex 02h (transmission type) of the objects defines the transmis- sion type. The PDO only responds to a request via bit RTR if RTR trans- mission is enabled for a PDO. The subindex values for the RTR bit are:
Objects 1403h, 1803h subindex 02h, | Meaning |
"transmission type" |
|
|
|
252 | RTR active, synchronous |
|
|
253 | RTR active, asynchronous |
|
|
Table 3.8 Subindexes for using the bit
An overview of all values for the subindex 02h can be found in the object dictionary for the corresponding object.
The product cannot request PDOs, but it can respond to the request of
PDOs.
3.4.2.1Dynamic and static PDO mapping
Dynamic PDO mapping The settings for PDO mapping are defined in an assigned communica- tion object for each PDO. If the PDO mapping settings for a PDO can be changed, this is referred to as dynamic PDO mapping for the PDO. Dy- namic PDO mapping enables flexible combination of different process data during operation.
Static PDO mapping Static PDO mapping means that all objects are mapped in accordance
with a fixed setting in the corresponding PDO.
Properties of the integrated drive. The integrated drive supports 2 PDOs, the communication objects T_PDO4 and R_PDO4. These two PDO4 are enabled by default.
These PDOs are mapped statically, i.e. they cannot be configured but only read. The indexes for the permanently entered objects can be read from the PDO mapping object range:
•Object 1403h: receive PDO4 communication parameter
•Object 1603h: receive PDO4 mapping
•Object 1803h: transmit PDO4 communication parameter
•Object 1A03h: transmit PDO4 mapping
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