National Instruments SCC-TC02 Thermometer User Manual


 
© National Instruments Corporation 7 SCC-TC Series Thermocouple Input Modules User Guide
You can use the following formulas to convert the cold-junction sensor
voltage to cold-junction temperature:
where T
K
is the temperature in kelvin.
where
a = 1.295361 × 10
–3
b = 2.343159 × 10
–4
c = 1.018703 × 10
–7
R
T
is the resistance of the thermistor in ohms.
where V
TEMPOUT
is the output voltage of the cold-junction sensor.
where T(°F) and T(°C) are the temperature readings in degrees Fahrenheit
and Celsius, respectively.
Note V
TEMPOUT
varies from 1.91 V (at 0 °C) to 0.58 V (at 55 °C). For best resolution, use
the maximum gain for this range on the analog input channel.
For the cold-junction sensor measurement accuracy, refer to the
Specifications section.
Uncompensated Connectors and Accuracy
If you are using an SCC-TC02 with an uncompensated SCC panelette,
temperature gradients between the module and the junctions on the
panelette affect the accuracy of your measurements.
T °C() T
K
273.15=
T
K
1
ab Rln
T
()cRln
T
()
3
++[]
--------------------------------------------------------------=
R
T
5000
V
TEMPOUT
2.5 V
TEMPOUT
--------------------------------------


,=
T °F()
T °C()]9[
5
------------------------ 32+=