Lake Shore Model 321 Autotuning Temperature Controller User’s Manual
3-6
Operation
The default display is shown below.
To change the curve, press the
Curve
button, then press either the
s
,
t
, or
Curve
button to
increment or decrement through the available curve selections. The curve numbers available are
0 through 12. When cycling through the displays, only the curves appropriate for the specified sensor
type will be displayed. To accept a new curve number, press the
Enter
button, or press the
Escape
button to cancel. The standard curves, with their curve number and temperature range, are given in
Table 3-1.
Table 3-1. Sensor Curves
Curve No.
Number of Lines
Range (K)
Abbreviation
Description
00
01
02
03
04
05
06
07
08
09
10
11
12
31
31
31
31
88
31
31
31
31
31
31
1 – 325
1 – 325
1 – 325
14 – 800
2 - 475
1.4 – 325
*
4 – 325
*
3 – 850
*
3 – 1272
* †
3 – 670
*
DRC D
DRC E1
DT-470
Plat.
DT-470
*
AuFe07%
AuFe03%
Type E
Type K
Type T
User
SoftCal
DT-500 DRC Curve D
DT-500 DRC Curve E1
DT-400 Series Sensors Curve 10
Platinum DIN Curve
DT-400 Series Sensors Curve 10
Reserved
AuFe 0.07% vs. Chromel
AuFe 0.03% vs. Chromel
Type E
Type K
Type T
User Curve or Precision Option
SoftCal Curve
*
Values are for thermocouples with compensation. Uncompensated, the thermocouple can use the full ±45 mV range.
†
Display reading is limited to 999.9 in K. For higher readings, change units to °C.
3.2.6 SoftCal
SoftCal is used to improve the accuracy of a DT-400 Series Silicon Diode Sensor. The SoftCal
feature enables the user to reduce the error between a silicon diode and the Standard Curve 10 used
by the controller to convert the input voltage from the diode to a corresponding temperature. In short,
SoftCal provides the means to generate inexpensive calibrations for DT-400 Series sensors used with
the Model 321 Temperature Controller.
The Lake Shore DT-400 Series Sensors incorporate remarkably uniform sensing elements that
exhibit precise, monotonic, and repeatable temperature response in the range from 2 K to 475 K.
Temperature characteristics are extremely stable and predictable, and exhibit excellent uniformity
from device to device. As a result, these sensors can be routinely interchanged with one another. It is
this diode feature that makes the use of SoftCal possible.
For the DT-400 Series diodes, five tolerance bands of tracking accuracy are available. See Figure
3-3. Band 11 sensors offer absolute accuracy to within ±0.25 K at low temperature, and to within
±0.5 K at room temperature. At the other end of the spectrum, Band 13 sensors are accurate to within
±1.0 K a low temperature, and to within ±1.0% of temperature or better from 100 K to 475 K. If better
accuracy is required, SoftCal can be employed with the Model 321 to improve the absolute accuracy
of the sensor.
