Fitting to a Equivalent Circuit: Best nonlinear fit converges to one set of numbers

[Sheel]

Hello,

I am using the constrained nonlinear curve fit to fit a set of impedance data to an RC circuit model.

I tried to emulate the code posted here, retailored for my model.

However, when I run the Vi. The fitting function seems to converge to one value for the fit, rather than producing a fittled line.

I was hoping someone could help me spot my error. 

I attached the Fit Vi and the Function Vi with the fitting function.

The Fit.Vi has a sample set of data included in it.

Thank you!

Sheel

[Bob_Schor]

Your Fit Test VI has nothing wired to its inputs, no data, no frequency inputs, no R, C values.  The LM Fit function immediately "blows up" and errors out.

Bob Schor