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NI-DAQ, use the 

Thermistor_Convert

 function. The VI takes the output 

voltage of the temperature sensor, the reference voltage, and the precision 
resistance and returns the thermistor temperature.

Alternatively, you can use the following formulas:

T(°C) = T

K

 – 273.15

where T

 is the temperature in Kelvin,

where a = 1.295361 

× 10

–3

b = 2.343159 

× 10

–4

c = 1.018703 

× 10

–7

 = resistance of the thermistor in ohms,

where V

 is the output voltage of the temperature sensor,

where T(°F) and T(°C) are the temperature readings in degrees Fahrenheit 
and degrees Celsius, respectively.

Figure 2-16 shows an RTD (R

1

) connected to channel 12 on the SCXI-1331 

terminal block. The RTD is connected in the 4-wire configuration. It is 
recommended that you connect RTDs in a 4-wire configuration to 
eliminate the effects of lead resistance on the measurement. See the 

 section for more information.

Figure 2-16 shows a thermistor (R

2

) connected to channel 24 on the 

SCXI-1331 terminal block. The thermistor is connected in the 2-wire 
configuration. You can connect the thermistor in the two, four, or even 
1-wire input configurations. The choice is typically dictated by channel 
cost and required accuracy. The 4-wire configuration is ideal and provides 

1

ln

(

) c

ln

(

)

3

+

+

[

]

--------------------------------------------------------------

=

189 000

2.5

–

--------------------------------------









,

=

°F

( )

[T(

°C ) ]9

5

-----------------------

32

+

=