Lakeshore 325, Руководство пользователя, Страница: 82 / 166

Lake Shore Model 325 Temperature Controller User’s Manual
5-6 Advanced Operation
5.2.3 Copy Curve
Temperature curves can be copied from one location inside the Model 325 to another. This is a good way to make small
changes to an existing curve. Curve copy may also be necessary if the user needs the same curve with two different
temperature limits or needs to extend the range of a standard curve. The curve that is copied from is always preserved.
NOTE: The copy routine allows you to overwrite an existing user curve. Please ensure the curve number you
are writing to is correct before proceeding with curve copy.
To copy a curve, press the Curve Entry key. Press the
s
or
t
key until you see the following display.
Select With °®
Copy Curve
Press the Enter key. You can press the Escape key any time during this routine to return to the normal display.
Select Copy from °®
Curve 01 DT-470
Use the
s
or
t
key to select the curve number (01 through 35) to copy from. Once the curve number is selected, press
the Enter key. You will see the following message.
Select Copy to °®
Curve 21 User
Use the
s
or
t
key to select the curve number (21 through 35) to copy to. Press the Enter key to copy the curve. You
now return to the normal display.
5.3
SOFTCAL™
The Model 325 allows the user to perform inexpensive sensor calibrations with a set of algorithms called SoftCal. The
two SoftCal algorithms in the Model 325 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 user curve locations (21 through 35) in the instrument. The following sections describe the
data points needed from the user and the expected accuracy of the resulting curves.
Both DT-400 Series and platinum SoftCal algorithms require a standard curve that is already present in the Model 325.
When the user enters the type of sensor being calibrated, the correct standard curve must be selected. When calibration is
complete, the user must assign the new curve to an input. The Model 325 does not automatically assign the newly
generated curve to either input.
Calibration data points must be entered into the Model 325. These calibration points are normally measured at easily
obtained temperatures like the boiling point of cryogens. Each algorithm operates with one, two, or three calibration
points. The range of improved accuracy increases with more points.
There are two ways to get SoftCal calibration data points:

The user can record the response of an unknown sensor at
well controlled temperatures, or

The user can purchase a SoftCal calibrated sensor from Lake Shore. 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 to some users. 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.
The SoftCal calibration points are generated in a controlled calibration facility at Lake Shore for best accuracy. The
calibration points can be entered into the Model 325 so it can generate a curve. If the CalCurve service is purchased
with the calibrated sensor, the curve is also generated at the factory and can be entered like any other curve.