Thermistor temperatures back to resistance convertion

[teslac]

Greetings,

    I was wondering if anyone had a good technique or vi to convert thermistor temperatures back to actual temperature data.  I have a bunch of data that the wrong Steinhart-Hart constants were applied when the data was acquired and saved as temperature only.  I now need to post process the data using the wrong constants to get the raw resistance values and then correct the temperature by putting those resistance values back through the Steinhart-Hart equation with the correct constants.

[GerdW]

Hi teslac,

so you know the formula that was used to convert from R to T data: why don't you apply the inverse of that formula?

[teslac]

I did try that but have been getting erroneous results and was thinking maybe there was a vi that did the backwards conversion. 

[EamonnFPMcKernan]

If you want a quick way to sanity check your numbers use the calculator here to verify your Steinhart–Hart coefficients:

https://www.ametherm.com/thermistor/ntc-thermistors-steinhart-and-hart-equation

The solution to the inverse function is here:

https://en.wikipedia.org/wiki/Steinhart%E2%80%93Hart_equation

[GerdW]

Hi teslac,

---

@teslac wrote:

I did try that but have been getting erroneous results and was thinking maybe there was a vi that did the backwards conversion. 

---

So you have a problem with your VI, but you don't attach your VI so we cannot help you to debug it?

Instead you want someone else do the whole work for you for free?

[teslac]

My Apologize,

    I simply thought someone might know of a vi already written to perform this operation.  I used the equation solved for R published on the NI site but I likely made an error in the formula node and I am not the best C programer and even though it does not have any syntax errors it does produce wrong results.  I would greatly appreciate any help in pointing out my mistake. 

[GerdW · Accepted solution]

Hi teslac,

---

@teslac wrote:

even though it does not have any syntax errors it does produce wrong results.

---

Because you implemented the formula not correctly…

---

@teslac wrote:

I likely made an error in the formula node and I am not the best C programer

---

You don't need to be "the best C programmer" when you want to use LabVIEW: