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O
PERATION
Note
All of the controllers have automatic
tuning features which install optimum
tuning parameters to give the best
temperature accuracy. No manual
loading of tuning parameters is need-
ed. We recommend that you tune the
furnace to your specific application to
obtain the best results. To provide the
best temperature accuracy possible,
use these features when you install
your furnace and whenever you
change your application or procedure.
Note
Display will flash "tu.ER" if an error
occurs during tuning. To clear the
error and restart tuning, simultane-
ously press the PAGE and SCROLL
buttons and follow the steps outlined
in "Autotuning."
28
Running a Program
1.
Press the PAGE button until you reach the run
list (run LiSt).
2.
Press the SCROLL button until display reads,
"PrG."
3.
Press the UP or DOWN button to select the
program number you want to run.
4.
Press the RUN/HOLD button once to start the
program. (The RUN light will illuminate.)
Holding a Program
To put a running program on hold, press the RUN/HOLD
button. (The HOLD light will illuminate.)
Cancelling a Program
To cancel a program, hold the RUN/HOLD button down
until the RUN and HOLD lights go off.
Tuning your Furnace
The purpose of tuning your furnace is to match the char-
acteristics of your controller to the characteristics of the
process being controlled. Good control is evidenced by:
stable, straight-line control of the setpoint temperature
with no fluctuations; No overshoot or undershoot of the
setpoint temperature; Rapid restoration of the setpoint
temperature when external disturbances cause deviations
from the setpoint.
Gain Scheduling
Gain scheduling is the automatic transfer of control
between to sets of PID values. The 2408 controller does
this at a presettable process value. Gain scheduling is
used for difficult control processes which show large
changes in their response time or sensitivity at high or low
temperatures, or when heating or cooling.
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