Lake Shore Model 218 Temperature Monitor User’s Manual
Special Features
5-5
Copying Curves (Continued)
Use the
s
or
t
key to select the curve number to copy from. Once the curve number is selected,
press the
Enter
key. You will see the following message.
Use the
s
or
t
key to select the input number (1 – 8) of the curve to copy to. Press the
Enter
key to
copy the curve. You now return to the normal display.
5.2 SOFTCAL™
The Model 218 performs inexpensive sensor calibrations with two algorithms called SoftCal™. These
algorithms work with DT-400 Series Silicon Diode sensors and Platinum Sensors. They create a new
temperature response curve from the standard curve and known data points entered by the user. The
new curve loads into one of the eight user curve locations. These paragraphs describe the data points
needed from the user and the expected accuracy of the resulting curves.
Both DT-400 and Platinum SoftCal™ algorithms use an existing standard curve in the Model 218. The
new curve will be named SCAL DT # or SCAL PT #. When calibration is complete, the user must select
the new curve for the input; the Model 218 does not automatically choose the newly generated curve for
any input.
Each algorithm operates with one, two, or three calibration points. The range of improved accuracy
increases with more points. The calibration points are normally measured at easily reached
temperatures like the boiling point of cryogens.
There are two ways to get SoftCal™ calibration data points: The user records the response of an
unknown sensor at well controlled temperatures, or the user buys a Lake Shore SoftCal™ calibrated
sensor. There are advantages to both methods.
•
User:
When the user can provide stable calibration temperatures with the sensor installed, SoftCal™
calibration eliminates errors in the sensor measurement as well as the sensor. Thermal gradients,
instrument accuracy, and other measurement errors can be significant. Calibration can be no better
than user-supplied data.
•
Purchased:
Lake Shore sensors with SoftCal™ calibration include a set of calibration points in the
calibration report. Lake Shore generates these points in a controlled calibration facility for best
accuracy. Users enter the calibration points into the Model 218 to generate a curve. If the user buys
the CalCurve™ service with the calibrated sensor, the factory generates a curve that can be entered
like any other curve.
