curve fitting express Vi and Trigger and Gate express Vi

[mcj23]

Hi,

Iam measuring the voltage from a thermocouple using the 6008 daq and daq assisstant in labview. I then have this connected to the trigger and gate express VI to capture the step function response. this is connected to the curve fitting express VI using a non-linear model a*exp(b*x) which works find. However when i add a c coefficient (a*exp(b*x)+c) to my non-linear model the trigger doesnt work has anyone experienced this before? I am also trying to measure the time constant and wondered if there is an efficient way to do this? new to labview.

Kind Regards

Martyn

[altenbach]

What is the meaning of "doesn't work"? Any error messages?

Can you show us your code?

[mcj23]

The trigger picks up my step response when i fit the model a*exp(b*x) but not when i use a*exp(b*x)+c. I have attached my code.

[altenbach]

Sorry, code exclusively containing express VIs and dynamic data is way too opaque for me to troubleshoot.

Is there a way to get typical input data for the curve fitting express VI? Can you run the VI until the "data" graph contains data, then stop the VI and make the graph data the default (right-click...data operations...make current value default). Now save the VI under a new name and attach it once more.