Additional Information
The scaling type of a thermocouple measurement is defined as either
Polynomial or
Table. The scaling type used in a thermocouple acquisition will determine the range of temperatures that can be accurately calculated from the measured raw voltage values.
For
Polynomial, the measured voltage values are scaled using an Nth order polynomial equation. For most thermocouples, the equation for converting voltage to temperature is the following:
where
t90 is the temperature in degrees Celsius,
E is the voltage in millivolts, and
Di is a coefficient determined by the thermocouple type and temperature range. The accuracy of a polynomial fit greatly reduces after a certain range, so the DAQmx
Polynomial scaling type will only let you set a min and max temperature that is known to be accurate for a given thermocouple.
By setting the scaling type to
Table, a wider temperature range can be measured for K, N, T, B, and E type thermocouples.