Yamatake SDC35, User Manual

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5 - 4 Auto Tuning (AT) Function
5-29
Chapter 5. DETAILED DESCRIPTION OF EACH FUNCTION
The auto tuning (AT) function is used when the PID constants are set automatically with the control method set at
“Fixed PID” ([CtrL = 1]).
The AT function can be used when the control method is set to “Fixed PID”.
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Starting procedures
(1) Make sure that the PV input or operation end (heater power, etc.) is
controllable.
(2) Using the [r- -r] setup of the mode bank, multi-status display, and LED
monitor, make sure that the operation is in the RUN mode. If the indicator
[rdy] is lit and the operation is in the READY mode, change the mode to the
RUN mode.
(3) Make sure that the mode indicator [man] is off and the operation is in the
AUTO mode. If the indicator [man] is lit and the operation is in the MANUAL
mode, change the mode to the AUTO mode.
(4) Set the parameter setting [AT Stop/Start] to “AT start ([At] = [At.on])”.
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Stopping procedures
The AT function is completed automatically. To stop the AT function, which is
running, change the parameter setting [AT Stop/Start] to AT stop ([At] = [At.oF]).
Additionally, the AT function is stopped when changing the READY mode to the
MANUAL mode.
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Display during execution of AT
The decimal point at the 1st digit of the upper display (right end digit) flashes
twice repeatedly while the AT function is running. When the AT function is
completed and the PID constants are changed, this LED goes off.
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Operation during execution of AT
The AT function calculates the PID constants using the limit cycle.
(1) When the AT function is started, a point, where the SP and PV deviations are
split to “2:1”, is determined as ON/OFF change point of the manipulated
variable (MV).
(2) When the limit cycle is judged as stable, the PID constants are changed and the
AT function is completed.