According to the graph, the number of data items for one fluctuation period is approximately
1,000. When the task period of the assigned periodic task is 1 ms and the number of samplings
is 100, the data sampling period is 10 µs. If the fluctuation frequency of the Ch1 Analog Input
Value is calculated, it will be as follows.
Fluctuation frequency =
1
Fluctuation period
=
1
1,000
×
10 [µs]
= 100 [Hz]
4
Calculate the set value of moving average count for the moving average filter that attenuates
the signal of the fluctuation frequency.
Use the following formula to calculate the set value of moving average count.
Set value of moving average count =
(1 ÷ Digital Filter Processing Period [µs]) × 1,000,000 [Hz]
ƒ
N
[Hz]
Digital Filter Processing Period
on page 8 - 19 for information on the Digital Filter
Processing Period.
When the sampling period is 10 µs, the Digital Filter Processing Period is 5 µs. The fluctuation
frequency is the value calculated in step 3. If the moving average count is calculated, it will be
as follows.
Set value of moving average count =
(1 ÷ Digital Filter Processing Period [µs]) × 1,000,000 [Hz]
ƒ
N
[Hz]
=
(1÷5 [μs]) × 1,000,000 [Hz]
100 [Hz]
= 2,000 [times]
5
Set the moving average count for the Ch1 Moving Average Filter 1 to 2,000 times.
Refer to
on page 8 - 27 for how to set the moving average count.
6
Execute the program that use the High-speed Analog Inspection Library of Sysmac Library and
export the log data to a CSV file to check the effectiveness of the Ch1 Moving Average Filter 1.
7
Open the exported CSV file in Microsoft Excel, and then create a broken line graph with the
specifications below.
Item
Specification
Vertical axis
Analog input value after filtering
Horizontal axis Number of data items
Set the same display range for the vertical axis and the horizontal axis as step 2.
8
Check the effectiveness of the Ch1 Moving Average Filter 1 on the broken line graph.
Appendices
A - 24
NX-series Analog I/O Units User’s Manual for High-speed Analog Input Units (W592)
