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MELSEC-Q
3 SPECIFICATIONS
(3) Primary delay filter
A digital value whose transient noise has been smoothed is output according to
the preset time constant.
The degree of smoothing varies with the time constant setting.
The relational expression of the time constant and digital output value is indicated
below.
[If n = 1
*1
]
Yn = 0
[If n = 2]
Yn = yn-
1
+
t
(yn - yn-
1)
t + T
[If n
3]
Yn = Yn-
1 +
t
(yn - Yn-
1)
t + T
Yn: Current digital output value yn: Pre-smoothing digital output value
Yn-
1: Immediately preceding digital
output value
Yn-1: Immediately preceding
pre-smoothing digital output value
n: Sampling count
t: A/D conversion time (0.01s)
TA: Time constant (s)
1: The A/D conversion completed flag turns ON when n 2.
[Example 1] Digital output value when the analog input value varied from 0 to 1V
Under the condition that the Q64AD-GH is used with an input range
of 0 to 10V, the digital output value with a time constant setting of
1000ms (1s) changes as shown in the figure below.
When the analog input value comes to 1V, and then 1000ms (1s)
has elapsed, the digital output value reaches 63.2% of the value
attained when the sampling processing is selected.
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