Lake Shore Model 332 Temperature Controller User’s Manual
4.8
MANUAL TUNING (Closed-Loop PID Control)
In manual PID mode, the controller will accept user-entered Proportional, Integral, and Derivative
parameters to provide three-term PID control. Manual heater power output can be set manually in open
loop and closed-loop control modes. For details on PID tuning refer to Paragraph 2.7.
To place the controller in Manual PID tuning mode, press the
AutoTune
key, and press the
s
or
t
key
until you see the following display.
Select for Loop 1 °®
Tune Mode Manual PID
Press the
Enter
key. The controller is now in Manual PID mode.
4.8.1
Manually Setting Proportional (P)
The proportional parameter (also called gain) is the P part of the PID control equation. It has a range
of 0 to 1000 with a resolution of 0.1. Enter a value greater than zero for P when using closed-loop
control.
To set Proportional, press the
PID/MHP
key. You will see the following display.
Enter for Loop 1
Prop (P) 50.0
The Proportional (gain) limit is entered using the numeric keypad, which includes the numbers 0
–
9,
+/–, and decimal point. Proportional has a range of 0.1 to 1000 with a default of 50. Press the
Enter
key, then the
Escape
key to return to the normal display.
4.8.2
Manually Setting Integral (I)
The integral parameter (also called reset) is the I part of the PID control equation. It has a range of 0
to 1000 with a resolution of 0.1. Setting I to zero turns the reset function off. The I setting is related to
seconds by:
setting
seconds
1000
I
=
I
For example, a reset number setting of 20 corresponds to a time constant of 50 seconds. A system
will normally take several time constants to settle into the setpoint. The 50 second time constant, if
correct for the system being controlled, would result in a system that stabilizes at a new setpoint in
between 5 and 10 minutes.
To set Integral, press the
PID/MHP
key then press
Enter
until you see the following display.
Enter for Loop 1 I
Integ (I) 20.0
The Integral (reset) is entered using the numeric keypad, which includes the numbers 0
–
9, +/–, and
decimal point. Integral has a range of 0.1 to 1000 with a default of 20. Press the
Enter
key, then the
Escape
key to return to the normal display.
Operation
4-17
