5 I/O Refreshing
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NX-series Analog I/O Units User’s Manual for Analog Input Units and Analog Output Units (W522)
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 is used.
Refer to the user’s manual for the connected Communications Coupler Unit for information on the I/O
refreshing methods that you can use between the Communications Coupler Unit and the NX Units.
As an example, when an EtherCAT Coupler Unit is connected to the built-in EtherCAT port on an
NJ/NX-series CPU Unit or NY-series Industrial PC, the I/O refreshing methods that you can use
between the EtherCAT Coupler Unit and the NX Units are shown below.
Since the EtherCAT Coupler Unit can execute all I/O refreshing methods at the same time, you can use
NX Units with different I/O refreshing methods together in the EtherCAT Slave Terminal.
Methods of I/O Refreshing between the Communications Coupler
Unit and NX Units
I/O refreshing method name 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 With this I/O refreshing method, the timing to read inputs or to refresh out-
puts is synchronized on a fixed interval between more than one NX Unit on
more than one Slave Terminal.
Time stamp refreshing
*1
*1. Neither the Analog Input Unit nor Analog Output Unit supports time stamp refreshing.
With this I/O refreshing method, the NX Units record the DC times when
inputs change or perform outputs at specified DC times. These times are
asynchronous to the NX bus refresh cycles. Data exchange between the NX
Units and EtherCAT Coupler Unit are performed cyclically on the NX bus
refresh cycles.
Input refreshing with input
changed time
With this I/O refreshing method, the Input Units record the DC times when
inputs changed.
Output refreshing with
specified time stamp
With this I/O refreshing method, the Output Units refresh outputs at specified
DC times.
Task period prioritized refresh-
ing
*2
*2. Necessary to use an EtherCAT Coupler Unit NX-ECC203. Neither the Analog Input Unit nor Analog Output
Unit supports task period prioritized refreshing.
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 synchronous I/O refreshing.
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