BECKHOFF DK9222-0711-0051 - Manual (Page 5)

XFC
XFC technology microincrements
Application Note DK9222-0711-0051
Synchronization of the strictly cyclical polling through the distributed clock function
High uniformity of the polling intervals can be achieved by using a local clock generator in the EtherCAT slaves, for example,
the distributed clock function within EtherCAT (see Fig. 2). This principle is based on measuring the protocol run times within
the bus and adjustment of the clock generator clocks in the individual fieldbus slaves. With DC, any run-time difference is
known exactly and can be compensated. The polling intervals of the EtherCAT slaves are thus adapted to the strictly cyclic
operation mode of the PLC. For distributed clock function, see the distributed clocks system description which is available from
the download area under www.beckhoff.com/english/download/ethercat.htm.
Fig. 2 Local clock generators in the field
New Automation Technology Beckhoff 5
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