Lake Shore Model 332 Temperature Controller User’s Manual
4.8.3
Manually Setting Derivative (D)
The derivative parameter (sometimes called rate) is the D part of the PID control equation. The rate
time constant should normally be somewhere between 1/4 and 1/8 the integral time in seconds, if
used at all. As a convenience to the operator, the Model 332 Derivative time constant is expressed in
percent of ¼ the integral time. The range is between 0 and 200%. Start with settings of either 0%,
50%, or 100%, and determine which setting gives you the type of control you desire. Do not be
surprised if the setting you prefer is 0. Note that by using a percent of integral time, derivative scales
automatically with changes in the integral value and does not have to be revisited frequently.
To set Derivative, press the
PID/MHP
key then press
Enter
until you see the following display.
Enter for Loop 1 D
Deriv (D) 0.0
The Derivative (rate) is entered using the numeric keypad, which includes the numbers 0
–
9, +/–, and
decimal point. Derivative has a range of 0 to 200 percent with a default of 0. Press the
Enter
key to
accept the new setting, then the
Escape
key to return to the normal display.
4.8.4
Setting Manual Heater Power (MHP) Output
Manual Heater Power (MHP) output is a manual setting of control output. It can function in two
different ways depending on control mode. In open-loop control mode, the MHP output is the only
output to the load. The user can directly set control output from the front panel or over computer
interface. In closed-loop control mode, the MHP output is added directly to the output of the PID
control equation. In effect, the control equation operates about the MHP output setting.
Manual heater power output setting is in percent of full scale. When using the heater on Loop 1,
percent of full scale is defined as percent of full scale current or power on the selected heater range.
Manual Heater Power Output setting range is 0% to 100% with a resolution of 0.001%.
When using Loop 2 analog voltage output the setting range is 0 to +100% and resolution is 0.001%
but the actual resolution of the output is only 0.003%.
To enter a MHP Output setting, press the
PID/MHP
key and press Enter until the following display
appears.
Enter for Loop 1
Manual Out 0.00%
The MHP Output setting is entered using the numeric keypad, which includes the numbers 0
–
9, +/–,
and decimal point. Press the
Enter
key, then the
Escape
key to return to the normal display.
4-18
Operation
