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11
For optimum performance, it may be necessary to change the PID
parameters within the controller. To tune the controller, do the following:
1.
Operate the unit in Manual Mode with a typical fluid within the container.
Toggle between ST PT 1 and ST PT 2 and watch for over or undershoot.
If there is significant overshoot access “VARIABLE 9” and reduce the
value by 4.
To access “VARIABLE 9” press the “VAR” (9) key, press “9”, and then
press “ENTER” (11). Key in the new value and press “ENTER” (11) to
store it into memory.
If there is no overshoot or undershoot, but the response was slow,
increase the value of “Variable 9” by 4.
Repeat the above procedure, changing the value of “VARIABLE 9” until
there is minimal overshoot and the ramp is smooth. Note that to fine tune
the controller, the value can be incremented in steps of 1 or 2 and not
necessarily a value of 4.
Variable 10 may be accessed and changed in the same manner.
2. Run the controller at ST PT 2. Increase “VARIABLE 10” by 4 and watch
for any oscillations around the setpoint. If no oscillations occur increase
“Variable 10” by 4 until oscillations begin.
3. After the onset of oscillations, reduce “VARIABLE 10” by 4.
4. Repeat steps 2 and 3 until minimal over and undershoot occur.
This is a trial and error process. After each change, record the setting and its
result. Variable 9 and 10 are initially set to 10 and 8 respectively.
Operation
PID Parameters