system id: estimated response and simulation mismatch

[doctorit7]

I'm using the SI Transfer Function Estimation express VI to model a plant transfer function for a system. The real data is a step response, where the stimulus is a flow rate ratio, and the response is the resulting droplet size (it's a fluid emulsion generation system, drop size decreases as pump ratio increases).

My problem comes in when I compare the simulated response data I see in the "preview" during configuration of the express VI, to a plot of the simulated response using the SI Model Simulation.VI - they do not match, the shape of the response is quite different. I'm fairly new to the control design and system id modules, so I assume I'm doing something wrong.

A screenshot of the express vi preview as well as front panel/block diagram is attached, along with the vi and data file.

TIA

[doctorit7 · Accepted solution]

After puzzling over this for two days, I finally figured out the error on my own, obviously only a few hours after I posted this question! (I should have posted sooner )

For the sake of posterity...

error #1: I'm using the data in an array form, and I forgot to wire in the sampling rate to the SI Model Simulation.vi
 
error #2: The transfer functions did not match in the express VI preview and on my front panel because I had not specified the realization type in the SI Convert to Transfer Function.vi  - default is "minimum" and it was therefore minimizing states. Changing it to full fixed that inconsistency.