LabVIEW provides different functions to convert resistance into temperature, however, sometimes there is a need to do it manually using the corresponding formula. In this example, the PT1000 RTD sensor will be used.
We use the Callendar-Van Dusen equation:
R(T) = R0(1 + A×T + B×T2 – 100×C×T3 + C×T4)
Where:
- R(T) = RTD resistance at temperature T (°C), replace with your acquired RTD resistance value
- R0 = RTD resistance at 0°C, R0 = 1000 Resistance at 0°C for PT1000 RTD
- A, B, and C constants are derived from experimentally determined parameters and regulated by the IEC751 standard. You can check the datasheet of the sensors because usually, the coefficients are provided by RTD manufacturers.
- For Pt100 and PT1000 RTD sensors, the constants are the following:
- A = 3.90830 × 10^(- 3)
- B = -5.77500 × 10^(- 7)
- C= 4.18301 × 10^(- 12) for -200°C ≤ T ≤ 0°C
- C= 0 for 0°C for ≤ T ≤ 850°C.
- Temperature (T) can be calculated by solving the quadratic equation if we ignore the coefficient C = 4.18301 × 10 - 12 for negative temperature:
- T = (-A + sqrt(A^2 - 4B×(1 - RT/R0))) / (2×B);
