Azbil DCP31 - Page 124

7-14
Chapter 7. PARAMETER SETUP

I O U t
(PID operation initial MV)
PIDoperationisstartedinthefollowingcasesusingthe
IOUt
set-
tingvalue:
•WhenthemodechangesfromREADYAUTOtoRUNAUTO
•WhenthepoweristurnedONintheRUNAUTO(orHOLD,
FAST,ENDAUTO)mode
•Atcompletionofauto-tuning
AsthePV,SPandPIDparameterssettingsbeararelationtoPID
operation,thefirstMV
resultingfromPIDoperationwillnotnecessarilymatchthe
IOUt

settingvalue.

R P I D
(PID operation initialization)
WhenSPchangessuddenlybyADV(advance)operation,rateac-
tioninPIDoperationmaycausetheMVintheoperationtochange
excessively.Forthisreason,excessivechangescanbesuppressedby
initializingPIDoperation.
However,asinitializationofPIDoperationmayresultinlostconti-
nuity,initializationmayadverselyinfluencePIDoperationdepend-
ingonthecircumstancesinwhichthecontrollerisbeingused.
InitializationON/OFFandconditionscanbeselectedbythe
RPID

setting.

S t
(smart-tuning method selection)
0: Smart-tuningisdisabled.
1: Thebrakevalueisfixedtoinhibitovershoot.
2: Overshootisinhibitedwhileautomaticallyreviewingthebrake
value.
•Whenthecontroldirectionissettoreverseaction,overshootis
inhibited.Whensettodirectaction,undershootisinhibited.Both
functionsarereferredtocollectivelyas“overshootinhibit.”
Whensetto1,thevalueofPIDparametersettingitem
BR
isused
asitistoinhibitovershoot.
Whensetto2,thevalueof
BR
isreviewedateachrise(reverse
action)orfall(directaction,andovershootisinhibitedwhilethe
valueisautomaticallyrewritten.
Reviewisexecutedonlyinthedirectioninwhichthe
BR
valueis
increased(overshootinhibiteffectbecomesmoreapparent).
Whenoperationiscarriedoutforalongtimewiththisparameter
setto2,overshootinhibitmayfunctiontoostrongly,anditmay
takealongtimetoarriveatSP.So,whenovershootdisappears,
notedownthe
BR
valueatthattime,set
ST
to1,andresetthe
BR

valuetothenoteddownvalue.