Omron E5CK - Page 54

CHAPTER 3 BASIC OPERATION
E5CK
3–24
Ă• AT (autoĆtuning) cannot be executed while operation is reset or during
ON/OFF control.
Ă• When you execute autoĆtuning, the optimum PID parameters are autoĆ
matically set by forcibly changing the manipulated variable to calculate
the characteristics (called the limit cycle method") of the control target.
During autoĆtuning, time counting is stopped and the AT" LED flashes.
Ă• 40%AT or 100%AT can be selected by the limit cycle of MV change width.
Specify [
] or [ ], respectively, in the AT execute/cancel" paĆ
rameter (level 1 mode).
Ă• During heating and cooling control, only 100%AT can be executed. (So,
[
] (40%AT) is not displayed.)
Ă• To cancel AT execution, specify ĂĂĂ
: AT cancel".
In order to set the limit cycle of MV change width to 40%, select 40%AT
to execute autoĆtuning with fluctuations in the process value kept to a
minimum. However, note that autoĆtuning takes longer to execute
compared with 100%AT.
The timing by which limit cycles are generated varies according to whether
or not the deviation (DV) at the start of AT execution is 10% fullĆscale or less.
Deviation at start of AT
execution y 10% FS
Deviation at start of AT
execution < 10% full-scale
Limit cycle of MV change
width 40%
Limit cycle of MV change
width 40%
Set point Set point
Start of AT
execution
End of AT
execution
Start of AT
execution
End of AT
execution
Time Time
Deviation 10%
full-scale
Deviation 10%
full-scale
In order to set the limit cycle of MV change width to 100%, select 100%AT
to shorten the AT execution time without worrying about fluctuations in
the process value.
Set point
Start of AT
execution
End of AT
e
x
ecut
i
o
n
Time
Limit cycle of MV
change width 100%
JAuto-tuning
(A.T.)
F 40%AT
F 100%AT