Azbil DCP31 - Auto-Tuning (AT)

6-15
Chapter 6. OPERATION
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Auto-tuning (AT)
WhenoperatingintheAUTOmodeineitheroftheRUN,HOLD,
FASTorENDmodes,settingvaluescanbeautomaticallywritten
tothePIDsetinusebyauto-tuning(AT).Thefollowingcanbe
selectedbyvariableparameterAtsetting.
0:ATisdisabled.
1:GeneralATisexecuted.
2:Overshoot-inhibitedATisexecuted.
3:ATbyneuralnetisexecuted.
• Auto-tuningdoesnotfunctionwhenprogrammerfunctionsare
selectedon3Dor5Kheat/cooloutputmodelsand5Goutput
models.
• Duringexecutionofauto-tuning,progressofprogramoperation
timestops.Accordingly,thecontrollerisinasimilarstatetothe
HOLDmodeevenintheRUNorFASTmodes.
• Auto-tuninginallinstancesinvolvescalculatingthedowntime
andcriticalsensitivityofthelineaccordingtotwolimitcycles
andPIDvaluesaccordingtosuitablecharacteristicequationsfor
each,andautomaticallywritingthesePIDvalues.
• Duringexecutionofauto-tuning,PVfluctuatesaccordingto
fluctuationsinMV.Beforeexecutingauto-tuning,makesurethat
fluctuationsinPVwillnotcausecontrollertrouble.
• Normally,suitablevaluesarewrittenbysettingvariableparam-
eterAtsettingto1or3.However,whenexecutingauto-tuning
onalinethateasilyovershoots,eithersetto2,oralsousesmart-
tuningforcarryingoutovershootinhibitcontrol.Settingto3
executesATbyneuralnetsothatthesuitablevalueiscalculated
forwiderrangeapplications.
• Thepointatwhichoutputatauto-tuningisinverted(lowerlimit
toupperlimit,andviceversa)isdeterminedasfollowsfromSP
andPVatstartofauto-tuning.