A/D Conversion Characteristics; Filter Processing - LG G3F-AD4A User Manual

Chapter 2. SPECIFICATIONS

2.5 A/D Conversion Characteristics

A/D conversion

2.5.1 Filter Processing

Filter processing noise or the quick change of input value helps to use a stable digital value compared with
analog value.
PVfn = ( 1 - α ) × PVn + α PVfn –
PVfn
PVn
PVfn-
α
Ex1) G3F-AD4A/G4F-AD2A
Offset value : –10 VDC, Gain Value : 0 VDC
(Voltage input range : -10 ~ 10 VDC, Digital output range : -192 ~ 16191)
When analog value is changed in the sequence like -10V, -5V, 0V, and 5V, filter output is shown as below.
Value of α
0.01
0.5
0.99
Ex2) G3F-AD4B
Voltage input range : 1 ~ 5 VDC, Digital output range : 0 ~ 16000
When analog value is changed in the sequence like 1V, 2V, 3V, and 4V, filter output is shown as below.
Value of α
0.01
0.5
0.99
That is, filter disable allows present A/D conversion value to be displayed and filter enable allows A/D
conversion value to be displayed by filter constant according to the relative importance between present
A/D conversion value and previous value.
Filter processing
Sampling (instantaneous value) processing
Average processing
: present filter output value
: present A/D conversion value
: previous filter output value
1
: Filter constant(the range: 0.01 to 0.99)
Filter constants used here are 1 to 99.
Filter output value
0 3960 7960
0 2000 5000
0 40 120
Filter output value
0 3960 7960
0 2000 5000
0 40 120
2 - 25
Number average processing
Time average processing
1
11960
α leaning to the previous value by 1 %
8500
α leaning to the previous value by 50 %
239
α leaning to the previous value by 99 %
11960
α leaning to the previous value by 1 %
8500
α leaning to the previous value by 50 %
239
α leaning to the previous value by 99 %
Remarks
Remarks