Rice Lake Tracer AV, Installation Manual

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Appendix
© Rice Lake Weighing Systems ● All Rights Reserved 37
6.6 Digital Filtering
The
Tracer AV
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 6-3 shows the digital filter parameters on the CONFIG menu.
Figure 6-3. Digital Filtering Parameters on the Configuration (CONFIG) Menu
Figure 6-4. Flow Diagram for Tracer AV Digital Filters
6.6.1 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 displayed weight. The value assigned to each parameter sets the number of readings received from
the preceding filter stage before averaging.
The overall filtering effect can be expressed by adding the values assigned to the three filter stages:
DIGFL3
For example, if the filters are configured as DIGFL1=4, DIGFL2=8, DIGFL3=8, the overall filtering effect is 20 (4 + 8 + 8). With
this 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.
6.6.2 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. When a specified 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
1
4
2
8
DIGFL1
32
16
64
1
4
2
8
DIGFL2
32
16
64
1
4
2
8
DIGFL3
32
16
64
8OUT
32OUT
16OUT
64OUT
DFSENS DFTHRH
2OUT
128OUT
4OUT
2DD
NONE
5DD
20DD
10DD
50DD
200DD
100DD
250DD
DIGFL1= n1 DIGFL2= n2 DIGFL3= n3
3rd Stage
Filter A verage
2nd Stage
Filter A verage
1st Stage
Filter A verage
Displayed
Value
n3
2nd Stage
Filter A verages
n2
1st Stage
Filter A verages
n1
A/D Readings