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02/2020 | ID 443025.06
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9.5.1
SM-Sync: Synchronization using SyncManager event
In the case of adjustment using a SyncManager event, the EtherCAT slaves synchronize using incoming data as the event.
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Cycle time
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Cycle time
Task
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Cycle time
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Data ready
PLL phase offset
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Fig. 12: SM-Sync – Synchronization using SyncManager event
The following times are significant for SM-Sync.
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Master cycle time
... Time within which a master task is continuously called up and processed.
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Slave cycle time
... Time within which a slave task is continuously called up and processed.
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PLL phase offset
... Time for which the beginning of the individual slave task can be shifted. The task beginning can only be shifted within the scope of the slave cycle time.
The quality of synchronization using SM-Sync suffers in the case of delays in the PDOs from master to slave. Because master jitter has an immediate impact on the slaves, this synchronization
method leads to a poorer result than an adjustment using distributed clocks.
