Easy Electronics xLogic Micro PLC - Page 193

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TimingDiagram
Thenature,mannerandspeedwithwhichtheAQchangesdependsontheparametersKCandTI.Thus,
thecourseofAQinthediagramismerelyanexample.Acontrolactioniscontinuous;thereforethe
diagramportraysjustanextract.
1. AdisturbancecausesthePVtodrop,asDirispositionedupwards,AQincreasesuntilPV
corresponds
againtoSP.
2. AdisturbancecausesthePVtodrop,asDirispositionedupwards,AQdecreasesuntil
PV
correspondsagaintoSP.
Diriscoordinatedtothebasicconductofacontrolloop.Thedirection(dir)cannotbechanged
duringthetermofthefunction.ThechangeinDirhereisshownforthepurposesofclarification.
3. AsAQissetto0bymeansoftheinputR,PVchanges.ThisisbasedonthefactthatPV
increases,
whichonaccountofDir=upwardscausesAQtodrop.
DescriptionofFunction
IftheinputA/Missetto0,thenthespecialfunctionissuesoutputAQwiththevaluethatyousetwith
parameterMq.
IftheinputA/Missetto1,thenautomaticmodecommences.AsanintegralsumthevalueMqisadopted,
thecontrollerfunctionbeginsthecalculationsinaccordancewiththeformulasgiveninControland
regulatebasics.TheupdatedvaluePVisusedtocalculateintheformulas.
UpdatedvaluePV=(PV*gain)+offset