Lenze ECSCAxxx - Manual (Page 450)

Appendix
General information about the system bus (CAN)
Process data transfer
14
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450 EDBCSXA064 EN 3.2
Synchronisation of PDOs with sync−controlled transmission
In order that the cyclic process data can be read by the controller or the controller accepts
the process data, a special telegram, the CAN sync telegram, is used in addition.
The CAN sync telegram is the trigger point for sending process data of the controller to the
master and transferring process data from the master to the controller.
A sync−controlled process data processing requires a corresponding generation of the CAN
sync telegram.
1.
CAN sync telegram CAN sync telegram
Cycle time
TPDOs RPDOs
2. 3.
Fig. 14−10 Sync telegram
1. After the CAN sync telegram has been received, the synchronous process data from
the controllers are sent to the master (TPDOs). They are read as process input data in
the master.
2. When the transmission process is completed, the process output data (of the
master) are received by the controllers (RPDOs).
All other telegrams (e.g. parameters or event−controlled process data) are accepted
acyclically by the controllers after transmission is completed. The acyclic data are not
displayed in the above illustration. They must be considered when the cycle time is
dimensioned.
3. The data in the controller is accepted with the next CAN sync telegram.
I
Tip!
The response to a CAN sync telegram is determined by the transmission type
selected.
)
Note!
Information on how to set the synchronisation can be found from
^ 166.