Mitsubishi Electric MELSEC iQ-F FX5 User Manual page 33

Digital filter
The digital filter can remove fluctuation of the analog input value below the digital filter setting value.
The relationships among the digital output, digital filter setting, and analog input values are as follows.
■Digital filter setting value > Analog input value fluctuation
If the analog input value fluctuation is smaller than the digital filter setting value, the conversion value resulting from removal
of the fluctuation will be stored as the digital output value. Note that the fluctuation range below the digital filter setting value
must satisfy the following expression.
Fluctuation range below the digital filter setting value < Conversion cycle  10 times
■Digital filter setting value  Analog input value fluctuation
When the analog input value fluctuation is larger than or equal to the digital filter setting value, the conversion value following
the analog input value is stored as the digital output and digital operation values.
Analog input value
Digital output value
Digital filter requires the A/D conversion values for 23 times to remove the fluctuation which is smaller than the digital filter
setting value. Therefore, when using the digital filter, the first digital output value is updated at the timing when the A/D
conversion values for 23 times are completed.
From the second time on, the digital output value is updated every conversion cycle.
■Digital filter conversion cycle
The digital filter conversion cycle varies depending on the setting value of the digital filter fluctuation range setting. The
conversion cycle of the digital filter in operation is stored in 'CH1 Digital filter conversion cycle monitor' (Un\G411).
After CH1 digital filter conversion cycle monitor (Un\G411) turns on and off the operating condition setting
request, "0" is stored for any of the following states.
• A/D conversion not allowed
• Operates in the A/D conversion method other than the digital filter.
• "Averaging process specification setting range error" (error code: 191H) occurs
• "Time average setting range error" (error code: 192H) occurs
• "Count average setting range error" (error code: 193H) occurs
• "Moving average setting range error" (error code: 194H) occurs
• "Primary delay filter constant setting range error" (error code: 195H) occur
• "Digital filter setting range error" (error code: 19DH) occur
• "Digital filter fluctuation width setting range error" (error code: 19EH) occur
The digital output value follows
the analog input value.
Digital filter setting value
Digital filter setting value
Converted to a digital output value from which the fluctuation is removed.
(The variation width is less than (conversion cycle × 10 times))
Time
1
1 FX5-4AD
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1.4 Functions