Digital Filtering; Digflx Parameters; Dfsens And Dfthrh Parameters - Rice Lake Revolution SURVIVOR 420HE Installation Manual

1.7

Digital Filtering

The 420 Plus uses averaged digital filtering to reduce the effect of vibration on weight readings. Adjustable
threshold and sensitivity functions allow quick settling by suspending filter averaging, allowing the weight reading
to jump to the new value. Figure 1-3 shows the digital filter parameters on the CONFIG menu.
DIGFL1
2
4
8
16
32
64
1
Figure 1-3. Digital Filtering Parameters on the Configuration (CONFIG) Menu
DIGFL1= n1
n1
A/D Readings
1st Stage
Filter A verage
1.7.1

DIGFLx Parameters

The first three digital filtering parameters, DIGFL1,
DIGFL2, and DIGFL3, are configurable filter stages
that control the effect of a single A/D reading on the
displaye d w eight. T he value assigned to ea ch
parameter sets the number of readings received from
the preceding filter stage before averaging (see
Figure 1-4).
The overall filtering effect can be expressed by adding
the values assigned to the three filter stages:
DIGFL1 + DIGFL2 + DIGFL3
Fo r e x a mp l e , i f t h e f i lt e r s a r e c on f i gu r e d a s
DIGFL1=4, DIGFL2=8, DIGFL3=8, the overall
f i l t e r i n g e f f e c t i s 2 0 ( 4 + 8 + 8 ) . Wi t h t h i s
configuration, each A/D reading has a 1-in-20 effect on
the displayed weight value. Setting the filters to 1
effectively disables digital filtering.
DIGFL2 DIGFL3
2 2
4 4
8 8
16 16
32 32
64 64
1 1
DIGFL2= n2
n2
1st Stage
Filter A verages
2nd Stage
Filter A verage
Figure 1-4. Flow Diagram for
DFSENS DFTHRH
8OUT
16OUT
32OUT
64OUT
128OUT
2OUT
4OUT
DIGFL3= n3
n3
2nd Stage
Filter A verages
3rd Stage
Filter A verage
420 Plus
Digital Filters
1.7.2

DFSENS and DFTHRH Parameters

The three digital filters can be used by themselves to
eliminate vibration effects, but heavy filtering also
increases settling time. The DFSENS (digital filter
sensitivity) and DFTHRH (digital filter threshold)
parameters can be used to temporarily override filter
averaging and improve settling time:
• DFSENS specifies the number of consecutive
scale readings that must fall outside the filter
threshold (DFTHRH) before digital filtering is
suspended.
• DFTHRH sets a threshold value, in display
divisions. Whe n a spe cifie d number of
consecutive scale readings (DFSENS) fall
outside of this threshold, digital filtering is
suspended. Set DFTHRH to NONE to turn off
the filter override.
NONE
2DD
5DD
10DD
20DD
50DD
100DD
200DD
250DD
Displayed
Value
45