Temperature Measurement with Pt100 and Pt1000

Updated May 19, 2020

Reported In

Hardware

  • NI-9216
  • NI-9217
  • NI-9226
  • PXIe-4357
  • NI-9219

Issue Details

  • I would like to connect Pt100 and Pt1000 temperature sensors to my analog and temperature input modules, but I don't know if the sensors are compatible with the specific modules.

Solution

Pt100 has a nominal resistance of 100 Ohms at 0°C. The Pt1000 has 1000 Ohms nominal resistance at 0°C. In both cases Pt stands for platinum.

For Pt100 and Pt1000 measurements specifically, we offer C Series Temperature Input Modules, a C Series Universal Analog Input Module, and a PXI Temperature Input Module:
 
  • NI 9216 C Series Temperature Input Module (for Pt100, 0-400 Ohm, -200°C to 850°C)
  • NI 9217 C Series Temperature Input Module (for Pt100, 0-400 Ohm, -200°C to 850°C)
  • NI 9226 C Series Temperature Input Module (for Pt1000, 0-4000 Ohm, -200°C to 850°C)
  • NI 9219 C Series Universal Analog Input Module (for both Pt100, 0-505 Ohm and Pt1000, 0-5050 Ohm)
  • NI PXIe-4357 PXI Temperature Input Module (for Pt100, 0-400 Ohm, -200°C to 850°C)

Additional Information

While the 9216 and the 9226 are designed for the Pt100 and Pt1000 respectively, and while it's not advised, you can use either module for each RTD. Both the scaling and range will be off, since the modules internal circuitry are designed for either measurement. Additional external circuitry is necessary to shift the measurement up or down to be in the acceptable resistance range for the module.Shift the measurement down using a voltage division circuit, or shift the measurement up using a voltage amplification circuit. By putting a second resistor in series, or in parallel, and by sizing your resistor accurately, you can take your voltage measurement in the range accepted by the module. The scaling can be compensated for programmatically by adding math functions to correlate each voltage to the appropriate temperature. Again, National Instruments does not recommend this method, but it is possible.