IM 04L20A01-01E
1-6
Filter/Moving Average
The filter and moving average are used to suppress the effects of noise that is riding on
the signal. Filtering is provided on the FX103. Moving average is provided on the
FX106 and FX112. The filter or moving average can be set on each channel.
Filter Function (FX103)
Suppresses the effects of noise above the frequency determined by the specified time
constant. The time constant can be set to 2 s, 5 s, or 10 s.
63.2% of the output value
2, 5, 10 s (time constant, the time it takes to reach 63.2% of the output value)
Output response curve (when using the filter)
Input
Effects of using filter (Output response for a step input)
Moving Average
The input signal of the measurement channel is set to the averaged value of the m
most current data points (the number of moving-averaged data points) acquired at the
scan interval. The number of moving-averaged data points can be set in the range 2
to 16.
The figure below shows an example indicating the operation of the buffer for the
moving average computation when the number of moving-averaged data points is set
to “5.”
1
2
3
4
5
10.0mV
5.0mV
0.0mV
–5.0mV
–10.0mV
0.0mV
15.0mV
10.0mV
5.0mV
0.0mV
–5.0mV
5.0mV
10.0mV
15.0mV
10.0mV
5.0mV
0.0mV
8.0mV
Deleted
Deleted
Moving average value
New data
New data
Buffer data at the
nth sampling
Buffer data at the
n+1th sampling
Buffer data at the
n+2th sampling
Integration Time of the A/D Converter
The FX100 uses an A/D converter to convert the sampled analog signal to a digital
signal. By setting the integration time to match the time period corresponding to one
cycle of the power supply or an integer multiple of one cycle, the power supply frequency
noise can be effectively eliminated.
The integration time of the A/D converter is selected from the table below.
Model Integration Time of the A/D Converter
FX103 Select 16.7 ms (60 Hz), 20 ms (50 Hz), or Auto
FX106/FX112 Select 16.7 ms (60 Hz), 20 ms (50 Hz), 100 ms, or Auto
• If “Auto” is selected, the FX100 will automatically detect the power supply frequency
and select 16.7 ms or 20 ms. Fixed to 20 ms on /P1 models that use the 24 VDC
power supply.
• Because 100 ms is an integer multiple of 16.7 ms and 20 ms, this setting can be used
to eliminate the power frequency noise for either frequency, 50 Hz or 60 Hz.
However, when the integration time is 100 ms, the scan interval is fixed to 2 s.
1.2 Functions of the Input Section
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