Primary Delay Filter - Mitsubishi Electric Melsec iQ-R Series User Manual

Primary delay filter

The A/D converter module smooths transient noise of an analog input according to the set time constant. The smoothed
digital output value is stored in the buffer memory.
Time constant is the time taken for the digital output value to reach 63.2% of the steady-state value. The degree of smoothing
changes depending on the setting of a time constant. The following shows the calculation formula of a time constant.
• Time constant = (Conversion cycle)  (Value set in 'CH1 Time average/Count average/Moving average/Primary delay filter
constant setting' (Un\G502))
The following table shows the relational expressions of a time constant, digital output values, and current number of sampling
(n).
Current number of sampling
n = 1
n = 2
n3
'A/D conversion completed flag' (XE) turns on when n  2.
Ex.
The following shows the digital output value of when an analog input value is changed from 0 to 1mA.
Item
Primary delay filter constant setting
After 4s from when the analog input value is changed to 1mA, the digital output value reaches 63.2% of the digital output
value of when the sampling processing is selected.
mA
1.2
1.0
0.8
63.2%
0.6
0.4
0.2
0
0 4
mA: Analog input value (mA)
t: Elapsed time (s)
digit: Digital output value
: Change of the analog input value
: Change of the digital output value
Setting method
1.
Set "Average processing setting" to "Primary delay filter".
[Navigation window]  [Parameter]  [Module Information]  Module model name  [Basic setting]  [A/D conversion
method]
2.
Set a value for "Time average/Count average/Moving average/Primary delay filter constant setting".
A/D conversion method
Primary delay filter
1 FUNCTIONS
28
1.5 A/D Conversion Method
Relational expression
Y = 0
n
Δt
Y = X + (X - X
n n-1 n
Δt + TA
Δt
(X - Y
Y = Y +
n
n n-1
Δt + TA
Setting
50
digit
1920
1600
1280
960
640
320
t
Setting range
1 to 500 (times)
Element
Y : Current digital output value
n
Y : Last digital output value
n-1
n: Number of sampling
)
X : Digital output value before smoothing
n-1
n
X : Last digital output value before smoothing
n-1
t: Sampling cycle
TA: Time constant
)
n-1