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Chapter 3 Basic Operations
3.6
Verifying PID Constants (AT and manual settings)
■ AT (auto-tuning)
● Explanation
3-10
●
When using auto-tuning, the program will force modifications in operation
volume to calculate the set point's optimal PID parameter, and calculate the
unique automatic settings of the controlled object (the "limit cycle method").
●
Select "on: Execute AT" execute AT (auto-tuning), select "off: Cancel AT"
to cancel AT (auto-tuning). When AT is finished, "on" will fall-back to "off"
automatically.
●
In the "adjustment level", the "proportional band (P)", "integral time (I)", and
"derivative time (D)" parameters indicate the AT (auto-tuning) results.
Adjustment Level
c
p
8.0
l. adj
i
233
l. adj
d
40
l. adj
When the "execute/cancel AT" parameter is set to "ON", AT (auto-tuning) is
activated. During AT execution, the "execute/cancel AT" parameter flashes on
the No. 1 display. When AT is finished, the "execute/cancel AT" parameter goes
off, and No. 1 display stops flashing.
Execute/cancel
AT
If while AT is executing you switch to the "operation level ", No. 2 display will flash
to indicate that AT is executing.
present value/
set point /
valve open percentage
When AT is executing, only the "communication writing", "run/stop" and
"execute/cancel AT" parameters may be changed. Other parameters may not be
changed.
Proportional Band
Integral Time
Derivative Time
at
at
off
on
l.adj
l.adj
When AT is executing
c
c
25
100
100.0
100.0
When AT is executing
No. 1 Display
No. 2 Display
25
100
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