Lake Shore Model 331 Temperature Controller User’s Manual
CHAPTER 5
ADVANCED OPERATION
5.0 GENERAL
This chapter covers the advanced operation of the Model 331 Temperature Controller. Advanced
operation consists of the functions related to temperature response curves. A temperature response
curve can be entered into the Model 331 in several ways: order it factory-installed (Paragraphs 2.2
and 7.2), create a SoftCal curve (Paragraph 5.3); load a curve via the computer interface (refer to the
various curve commands detailed in Paragraph 6.3), or enter a user-generated curve from the front
panel. Advanced functions include details on curve numbers and storage in Paragraph 5.1, front panel
curve entry operations in Paragraph 5.2, and SoftCal™ in Paragraph 5.3.
5.1
CURVE NUMBERS AND STORAGE
The Model 331 has 20 standard curve locations; numbered 1 thru 20. At present, not all locations are
occupied by curves; the others are reserved for future updates. If a standard curve location is in use,
the curve can be viewed using the edit operation. Standard curves can not be changed by the user, and
reserved locations are not available for user curves.
The Model 331 has 20 user curve locations numbered 21 thru 41. Each location can hold from 2 to 200
data pairs (breakpoints) including a value in sensor units and a corresponding value in kelvin. Using
fewer than 200 breakpoints will not increase the number of available curve locations. SoftCal generated
curves are stored in user curve locations.
5.1.1
Curve Header Parameters
Each curve has a set of parameters that are used for identification and to allow the instrument to use
the curve effectively. The parameters must be set correctly before a curve can be used for
temperature conversion or temperature control.
Curve Number:
1
–
41.
Name:
Defaults to the name
User Curve
for front panel entry. When entering a user curve over the
computer interface, a curve name of up to 15 characters can be entered.
Serial Number:
Up to a 10-character sensor serial number. Both numbers and letters can be entered
over computer interface, only numbers can be entered from the front panel.
Format:
The format parameter tells the instrument what breakpoint data format to expect. Different
sensor types require different formats. Formats for Lake Shore sensors are:
V/K:
Volts vs. Kelvin for Diode sensors.
Ω
/K:
Resistance vs. Kelvin for platinum RTD sensors.
Log
Ω
/K:
Log Resistance vs. Kelvin for NTC resistive sensors.
Limit:
Enter a temperature limit in Kelvin for the curve. Default is 375 K. Enter a setting of 9999 K if
no limit is needed.
Temperature Coefficient:
The unit derives the temperature coefficient from the first two breakpoints.
The user does not enter this setting. If it is not correct check for proper entry of those points.
A positive coefficient (
P
) indicates that the sensor signal increases with increasing temperature.
A negative coefficient (
N
) indicates that the sensor signal decreases with increasing temperature.
Advanced Operation
5-1
