Erice1984,

You can do a linear approximation but you are going to loose accuracy. Try doing a polynomial or exponential approximation. In EXCEL go to help and see how to add a trendline (it varies with the different versions of EXCEL). Obtaining the trendline is very simple. The trendline is going to give you a formula in the form of Y(X), X being the temperature and Y being the Resistance. Try with different options and settings until you get a good approximation. Then, you can use the resulting formula in your PBP program. That is with any value X (temperature) you can calculate a value Y (resistance).

You should get the whole temperature range 100-250 degrees F in your graph before doing an approximation, so you get better results.

This is one way to do it, which is very accurate. It all depends on the accuracy that you want for the resistance reading.

Hope that this helps.

Robert