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5 I/O Refreshing
NX-series Analog I/O Units User’s Manual for Analog Input Units and Analog Output Units (W522)
5-2 I/O Refreshing Methods
5
5-2-1 Types of I/O Refreshing Methods
5-2 I/O Refreshing Methods
This section describes I/O refreshing methods for the NX Units.
The I/O refreshing methods that you can use between the CPU Unit and the NX Units depend on the
connected CPU Unit.
Refer to the software user’s manual for the connected CPU Unit for information on the I/O refreshing
methods that you can use between the CPU Unit and the NX Units.
As an example, the I/O refreshing methods that you can use between the NX-series NX1P2 CPU Unit
and the NX Units are shown below.
Since the NX1P2 CPU Unit can execute all I/O refreshing methods at the same time, you can use NX
Units with different I/O refreshing methods together.
5-2-1 Types of I/O Refreshing Methods
Methods of I/O Refreshing between the CPU Unit and NX Units
I/O refreshing method name
*1
*1. Task period prioritized refreshing cannot be used for the NX1P2 CPU Unit.
Outline of operation
Free-Run refreshing With this I/O refreshing method, the refresh cycle of the NX bus and 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 con-
nected to a CPU Unit.
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 CPU 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.
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