5 I/O Refreshing
5 - 10
NX-series Analog I/O Units User’s Manual for Analog Input Units and Analog Output Units (W522)
• The Communications Coupler Unit performs I/O refreshing for NX Units. (Refer to (a) in the figure
below.)
• The NX Units read inputs or refresh outputs at the time of I/O refreshing. (Refer to (b) in the figure
below.)
• The Communications Coupler Unit can read the most recent input value at the time of I/O refreshing
and the NX Units can control the most recent output value at the time of I/O refreshing. However, the
timing to read inputs or to refresh outputs for each NX Unit in the Slave Terminal does not occur at
the same time. (Refer to (c) in the figure below.)
• The interval of I/O refreshing varies with the processing conditions of the Communications Coupler
Unit or the host communications master. Therefore, the interval of the timing to read inputs or to
refresh outputs for NX Units is not always the same. (Refer to (d) in the figure below.)
z Inputs
• The Analog Input Units repeatedly perform AD conversion in the order of inputs for which the used
channels are set to enable. AD conversion is not synchronized with I/O refreshing of the NX bus.
• At the time of I/O refreshing, the Communications Coupler Unit reads the converted values from
the NX Unit for one Unit that AD conversion is complete before the timing to read inputs.
Description of Slave Terminal Operation
I/O refreshing
of the NX bus
Analog Input Unit A
Analog Input Unit B
Timing to read inputs for each Unit is not simultaneous.
Timing to read
inputs
Input 1
Input 2 Input 3 Input 4 Input 1 Input 2 Input 3 Input 4 Input 1 Input 2 Input 3 Input 4 Input 1 Input 2 Input 3 Input 4
Input 3 Input 4
Input 4 Input 1 Input 2
Input 4
Input 1 Input 2
Input 4 Input 1 Input 2 Input 4
(c)
(b)
(d) Interval of the timing to read inputs is not constant.
(a) I/O refreshing for NX Units
Input refreshing Output refreshing
To Next Page
Loading...
Need help?
General
