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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
5-2-4 Free-Run Refreshing
z Outputs
• The Analog Output Units repeatedly perform DA conversion in the order of outputs for which the
used channels are set to enable. The outputs are refreshed once per DA conversion cycle for one
Unit when DA conversion of the last output is complete. The refreshing is not synchronized with
I/O refreshing of the NX bus.
• At the time of I/O refreshing, the Analog Output Units perform DA conversion with the refreshed
output set values from the outputs before the start of conversion.
Add NX Units that support Free-Run refreshing to the CPU Unit configuration or Slave Terminal config-
uration.
After you add the NX Units, set an I/O refreshing method depending on the connected CPU Unit or
Communications Coupler Unit so that these NX Units operate with Free-Run refreshing.
Refer to 5-2-2 Setting the I/O Refreshing Methods on page 5-7 for the setting procedure of the I/O
refreshing method.
Settings
Analog Output Unit A
Analog Output Unit B
Output 1 Output 2 Output 3 Output 4 Output 1 Output 2 Output 3 Output 4 Output 1 Output 2 Output 3 Output 4 Output 1 Output 2 Output 3 Output 4
Timing to refresh outputs for each Unit is not simultaneous.
Refresh the output set
values by output refreshing
Output 1 Output 2 Output 3 Output 4 Output 2 Output 3 Output 4Output 1Output 4
Output 1: Previous output set values
Output 2 to 4: Current output set values
Output 1 to 4:
Previous output
set values
Output 1 to 4:
Current output
set values
Output 1 to 2:
Previous output
set values
Output 3 to 4:
Current output
set values
Output 1 to 4:
Current output
set values
Output 1 to 4:
Current output
set values
I/O refreshing
of the NX bus
(c)
(b)
(d) Interval of the timing to refresh outputs is not constant.
(a) I/O refreshing for NX Units
Input refreshing Output refreshing
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