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5 I/O Refreshing Methods
5 - 4 NX-series Position Interface Units User’s Manual (W524)
5-2 I/O Refreshing Methods
This section describes I/O refreshing for Position Interface Units.
The I/O refreshing methods that you can use between the Communications Coupler Unit and the NX
Units depend on the Communications Coupler Unit that you use.
The I/O refreshing methods that you can use between an EtherCAT Coupler Unit and the Position Inter-
face Units when the EtherCAT Coupler Unit is connected to the built-in EtherCAT port on an
NJ/NX-series CPU Unit are listed below.
With an EtherCAT Coupler Unit, you can use all of the I/O refreshing methods at the same time. There-
fore, you can mix NX Units with different I/O refreshing methods on the same EtherCAT Slave Terminal.
Additional Information
The EtherCAT Slave Terminals with enabled distributed clocks and all EtherCAT slaves that
support DC synchronization execute I/O processing based on Sync0, which is shared on the
EtherCAT network. However, because the specifications and performance for the timing to read
inputs or to refresh outputs for EtherCAT slaves and NX Units are different, the timing to read
inputs or to refresh outputs is not simultaneous.
Refer to the manuals for the EtherCAT slaves for information on the timing to read inputs or to
refresh outputs in EtherCAT slaves.
Free-Run refreshing is always used as the I/O refreshing method between the EtherNet/IP Coupler Unit
and the NX Units.
This section describes the settings of the I/O refreshing method for each Communications Coupler Unit.
5-2-1 I/O Refreshing Methods
EtherCAT Coupler Unit
I/O refreshing method Outline of operation
Free-Run refreshing With this I/O refreshing method, the refresh cycle of the NX bus and the I/O
refresh cycles of the NX Units are asynchronous.
Synchronous I/O refreshing
*1
*1. This method is used when you use the MC Function Module in an NJ/NX-series Controller.
With this I/O refreshing method, the timing to read inputs or to refresh outputs
is synchronized on a fixed interval between more than one NX Unit on more
than one Slave Terminal.
Task period prioritized refresh-
ing
*1*2
*2. Unit version 1.2 or later and an NX-ECC203 EtherCAT Coupler Unit are required.
With this I/O refreshing method, shortening the task period is given priority
over synchronizing the I/O timing with other NX Units. With this I/O refreshing
method, the timing of I/O is not consistent with the timing of I/O for NX Units
that use simultaneous I/O refreshing.
EtherNet/IP Coupler Unit
5-2-2 Setting the I/O Refreshing Methods