Tracer AV Installation Manual - Rice Lake Weighing Systems

6.6 Digital FilteringThe Tracer AV uses averaged digital filtering to reduce the effect of vibration on weight readings. Adjustablethreshold and sensitivity functions allow quick settling by suspending filter averaging, allowing the weightreading to jump to the new value. Figure 6-3 shows the digital filter parameters on the CONFIG menu.DIGFL1DIGFL2DIGFL3DFSENSDFTHRH2228OUTNONE44416OUT2DD88832OUT5DD16161664OUT10DD323232128OUT20DD6464642OUT50DD1114OUT100DD200DD250DDFigure 6-3. Digital Filtering Parameters on the Configuration (CONFIG) MenuDIGFL1= n1 DIGFL2= n2 DIGFL3= n3n1A/D Readingsn21st StageFilter A veragesn32nd StageFilter A verages1st StageFilter A verage2nd StageFilter A verage3rd StageFilter A verageDisplayedValueFigure 6-4. Flow Diagram for Tracer AV Digital Filters6.6.1 DIGFLx ParametersThe first three digital filtering parameters, DIGFL1,DIGFL2, and DIGFL3, are configurable filter stagesthat control the effect of a single A/D reading on thedisplayed weight. The value assigned to eachparameter sets the number of readings received fromthe preceding filter stage before averaging (seeFigure 6-4).The overall filtering effect can be expressed by addingthe values assigned to the three filter stages:DIGFL1 + DIGFL2 + DIGFL3For example, if the filters are configured asDIGFL1=4, DIGFL2=8, DIGFL3=8, the overallfiltering effect is 20 (4 + 8 + 8). With thisconfiguration, each A/D reading has a 1-in-20 effecton the displayed weight value. Setting the filters to 1effectively disables digital filtering.6.6.2 DFSENS and DFTHRH ParametersThe three digital filters can be used by themselves toeliminate vibration effects, but heavy filtering alsoincreases settling time. The DFSENS (digital filtersensitivity) and DFTHRH (digital filter threshold)parameters can be used to temporarily override filteraveraging and improve settling time:• DFSENS specifies the number of consecutivescale readings that must fall outside the filterthreshold (DFTHRH) before digital filteringis suspended.• DFTHRH sets a threshold value, in displaydivisions. When a specified number ofconsecutive scale readings (DFSENS) falloutside of this threshold, digital filtering issuspended. Set DFTHRH to NONE to turn offthe filter override.Tracer AV Installation Manual - Appendix 37