For measuring temperatures there are many possibilities, one popular for cryogenics is the use of a silicon diode (among better but more expensive ones like Cernox sensors). A recent silicon diode that has a standard signal, i.e. does not require callibration, is the DT670 Si diode. The principle is based on the variation of the resistance of the diode with the temperature. Standard curve, as used in this program, is based on the voltage required to apply a 10 microAmp current. The following subroutine converts the voltage, in V, to the temperature of the junction in K.
The labview 2018 vi can be downloaded here.