BECKHOFF DK9222-0909-0005 - Manual (Page 2)

XFC
XFC technology oversampling
Application Note DK9222-0909-0005
Fig.  Local clock generators in the field
This is possible through the distributed clock function under EtherCAT (see Fig. 1): The local clock generators in the EtherCAT
slaves provide a uniform system time. The differences in internal protocol run-times of the bus between slaves are calculated,
and these micro-delays are compensated after synchronisation of the clocks in the EtherCAT slaves. The now unified system
time in the bus system allows reliable chronological relationships between different events within the system. For distributed
clock function see distributed clocks system description, available from the download area under http://www.beckhoff.com/
english/download/ethercat.htm .
The precision of the signal acquisition at I/Os is achieved through oversampling of the signal. This means that the signal is not
queried once per communication cycle as usual, but several times with a defined frequency within the cycle. The sampled data
are sent to the controller as a process data packet with the next communication cycle and analysed. For the user this has the
advantage that a finer subdivision can be achieved through oversampling with a typical motion application communication
cycle of 1 ms, without having to modify the cycle time. With an oversample frequency of 10 kHz and a cycle time of 1 ms the
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