Easy Electronics xLogic Micro PLC - Page 194

194
IftheupdatedvaluePV=SP,thenthespecialfunctiondoesnotchangethevalue
ofAQ.
Dir=upwards/+(timingdiagramnumbers1and3)
• IftheupdatedvaluePV>SP,thenthespecialfunctionreducesthevalueofAQ.
• IftheupdatedvaluePV<SP,thenthespecialfunctionincreasesthevalueof
AQ.
Dir=downwards/-(timingdiagramnumber2)
• IftheupdatedvaluePV>SP,thenthespecialfunctionincreasesthevalueof
AQ.
• IftheupdatedvaluePV<SP,thenthespecialfunctionreducesthevalueofAQ.
Withadisturbance,AQcontinuestoincrease/decreaseuntiltheupdatedvaluePV
againcorrespondstoSP.ThespeedwithwhichAQchangesdependsonthe
parametersKCandTI.IftheinputPVexceedstheparameterMax.,thentheupdated
valuePVissettothevalueofMax..IfthePVfallsshortoftheparameterMin.,then
theupdatedvaluePVissettothevalueofMin.
IftheinputRissetto1,thentheAQoutputisreset.AslongasRisset,theinputA/M
isdisabled.
SamplingTime
Thesamplingtimeisfixedat500ms.
Parametersets
InordertosimplifytheuseofthePIcontroller,theparametersforKC,TIandDirare
alreadygivenassetsforthefollowingapplications:
Parameterset Applicationexample ParameterKCParameterTI
(s)
Parameter
Dir
Temperaturefast Temperature,coolingcontrolof
smallspaces;smallvolumes
0,5 30 +
Temperatureslow Heating,ventilation,temperature,
coolingcontroloflargespaces;
largevolumes
1,0 120 +
Pressure1 Quick pressure change,
compressorcontrol
3,0 5 +
Pressure2 Slowpressurechange,differential
pressurecontrol(flowcontroller)
1,2 12 +