Omron NJ101-10 Series, Руководство пользователя

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Additional Information
Distributed Clock (DC)
This is a unique EtherCAT feature that enables precisely clock synchronization.
The DC-based clock synchronization enables sharing the same time between the EtherCAT
master and the slaves.
This enables the timing of the operation of the EtherCAT master and slaves to be synchronized
with the shared time.
EtherCAT Master
Slaves with a distributed clock
Operation timing is synchronized by sharing time
information between the EtherCAT master and slaves.
The clock that gives the standard network time is called a "reference clock".
The reference clock is provided either by the master or a slave that supports the function to pro-
vide a reference clock, to the other slaves. As described in the table below, whether the master
or slave provides a reference clock depends on the used CPU Unit.
When NX-series CPU Unit is Used When NJ-series CPU Unit is Used
The EtherCAT master of the NX-series CPU Unit Of the slaves that provide a reference clock, the
slave that is the closest to the EtherCAT master on
the wiring. In the above figure, the left most slave
of the slaves with the DC functionality.
*1
*1. Slaves with the DC functionality can provide a reference clock.
The EtherCAT master uses this reference clock to send frames so that the EtherCAT master
and slaves remain synchronized.
The slaves for which the distributed clock setting is enabled (i.e., synchronized slaves) perform
advanced time synchronization by performing input and outputs based on the reference clock.
3-1-2 Types of Communications
The following two methods are used to exchange data between master and slaves in EtherCAT com-
munications.
Communication type
Name of communication
type
Timing of processing Type of data
Cyclic communica-
tions Process data communica-
tions
(PDO communications) Constant
(process data communica-
tions cycle) PDO data
Message communica-
tions SDO communications When required. SDO data
3 EtherCAT Communications
3-4
NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (W505)