Lake Shore Model 331 Temperature Controller User’s Manual
5.1.2 Curve
Breakpoints
Temperature response data of a calibrated sensor must be reduced to a table of breakpoints before
entering it into the instrument. Each breakpoint consists of one value in sensor units and one
temperature value in kelvin. Linear interpolation is used by the instrument to calculate temperature
between breakpoints. From 2 to 200 breakpoints can be entered as a curve. The instrument will show
an error message on the display if the sensor input is outside the range of the breakpoints. No special
endpoints are required. Sensor units are defined by the format setting in Table 5-2.
Breakpoint setting resolution is six digits in temperature. Most temperature values are entered with
0.001 resolution. Temperature values of 1000 K and greater can be entered to 0.01 resolution.
Temperature values below 10 K can be entered with 0.0001 resolution. Temperature range for curve
entry is 1500 K.
Setting resolution is also six digits in sensor units. The curve format parameter defines the range and
resolution in sensor units as shown in Table 5-2. The sensor type determines the practical setting
resolution. Table 5-2 lists recommended sensor units resolutions. For most sensors, additional
resolution is ignored.
The breakpoints should be entered with the sensor units value increasing as point number increases.
There should not be any breakpoint locations left blank in the middle of a curve. The search routine in
the Model 331 interprets a blank breakpoint as the end of the curve.
5.2
FRONT PANEL CURVE ENTRY OPERATIONS
There are three operations associated with front panel curve entry: Edit curve, Copy curve, Erase
curve; as detailed below.
Edit
Curve
Edit allows the user to see any curve and enter or edit a curve
at any user curve location. Standard curves cannot be changed.
Refer to
Paragraph 5.2.1
Erase
Curve
Erase allows the user to delete a curve from any user curve
location. Standard curves cannot be erased.
Refer to
Paragraph 5.2.2
Copy
Curve
Copy allows the user to copy a curve from any location to any
user curve location. Curves cannot be copied into standard
curve locations.
Refer to
Paragraph 5.2.3
SoftCal
Allows creation of a new temperature curve from a standard
curve and known data points entered by the user.
Refer to
Paragraph 5.3
To begin a curve operation, press the
Curve Entry
key and the above selections appear. Press the
Next Setting
key until the desired operation is highlighted and press the
Enter
key. A curve screen
appears with the curve number highlighted. Change to the desired curve number with the up or down
arrow key, then press the
Enter
key to begin the desired curve operation.
5-2
Advanced Operation
