Azbil DCP31 - Page 110

6-16
Chapter 6. OPERATION
• Auto-tuningcanbestartedby
AT
,externalswitchinputsand
communications.Duringauto-tuning,theATLEDblinks.
• Ifoneormoreofthefollowingconditionsoccursduringauto-
tuning,auto-tuningiscanceledwithoutPIDconstantsbeingwrit-
ten,andtheATLEDgoesout.
 -Cancelby
AT
 -Cancelbyexternalswitchinput
 -Cancelbycommunications
 -Changeinmode(shifttoMANUALmodeorREADYmode)
 -Executionofautomaticmotorvalveopeningadjustmenton2G
outputmodels
 -WhenvariableparameterAtsettingischangedto“0”
 -Wheninput1becomesout-of-range
Handling Precautions
• Auto-tuning will not function properly unless the control target
is connected.
• The time from start to end of auto-tuning varies according to the
control target.
• When auto-tuning is executed, control is stopped, OFF and ON
outputs are switched in the case of relay output and voltage out-
put, and the manipulated variable upper and lower limits of the
currently selected PID set are switched several times in the case
of current output and position proportional output. If this causes
controller trouble, manually set the PID value.
• Sometimes a suitable PID value cannot be obtained depending
on the control target. If this happens, manually set the PID value.
PV
SP
2/3
1/3
1/3
2/3
PV
SP
PV>SP
At start At SP=PV operation
PV<SP
AT start
Normal end AT start Normal end
Time Time