Thermistors and RTDs require the following signal conditioning:

  • Current Excitation—Because RTDs and thermistors are resistive devices, your DAQ system must provide a current excitation source to measure a voltage across the device. This current source must be constant and precise.
  • 2-, 3-, and 4-Wire Configurations (RTDs only)—RTDs come in 2-, 3-, and 4-wire configurations. Therefore, your system must support the type of RTD you choose. Thermistors are typically 2-wire devices because they have higher resistance characteristics, thus eliminating lead resistance considerations.
  • Linearization —Neither RTD nor thermistor output voltage is linear with temperature. Therefore, your system must perform linearization either in hardware or software.