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APP NOTE

Simulate any resistive sensor.

ohmSTAR in table mode standing in for a temperature probe on a prototype data-logger board

If it changes resistance, ohmSTAR can stand in for it. Give it a two-column table. You dial the unit, it sets the ohms.

Three steps

  1. Build the table in a spreadsheet. Unit in column A, ohms in column B. Save as .txt.
  2. Load it over USB with the Lookup Table tool.
  3. Press TABLE. Your unit shows on top, ohms below.

Example: 10k NTC

β 3950 K, R25 = 10 kΩ
°CΩ
−20105,384.69
−1058,245.71
033,620.60
1020,174.58
2012,535.33
2510,000.00
405,301.47

Values are calculated from the standard curve. They aren't an accuracy spec.

File format: line 1 is the description (the LCD shows 20 characters). Line 2 is the number of decimals to show, 0 to 5. Then up to 256 rows of user value and ohms, separated by spaces, tabs or commas. Both columns must run in one direction. Write ohms in full: no K or M.

What it looks like

A thermistor resistance table open in Notepad
The .txt table.
Opened wall thermostat with a two-wire NTC thermistor probe in its terminal block
The box in use.

Which model

Look at both ends of your table. Above 5 MΩ: ohmSTAR, which goes to 25 MΩ. Need 0.01 Ω steps: ohmSTAR+. Neither goes below 1 Ω. In between: either one.