Use Polynomial on multiple Signals

[EUTstudent]

Hi there

I'm quite new to LabVIEW and need some help. I have 25 independent signals. Each signal has to be treated using a polynomial of second order with individual coefficients for each signal.

t_i=k_1,i*R_i^2+k_2,i*R_i+k_3,i

So far I managed to treat one Signal with the polynomial. But when I take multiple signals at a time the function gives me one result instead of 25. 

It also seems, that even though the DAQ-assistent uses 25 channels and the graphs show 25 signals as well, LabVIEW will really treat it as a array. For example I can display a numerical value resulting in the value of channel 0, but it will not display an array of 25 values which I would expect it to do... 

Can anybody tell me, what I am missing? Which function should I take? 

Kind regards and thanks for any help

[Gregory]

Hi EUTstudent,

At the moment the problem is not what you are missing, but what we are missing! Please post your code so we can have an idea of where to start helping you! 

For me, please post for LV 2012 or earlier. If you are using a later version of LabVIEW, just go to your project and click File >> Save for previous version...

[GerdW]

Hi student,

It also seems, that even though the DAQ-assistent uses 25 channels and the graphs show 25 signals as well, LabVIEW will really treat it as a array.

Yes.

For example I can display a numerical value resulting in the value of channel 0, but it will not display an array of 25 values which I would expect it to do...  Can anybody tell me, what I am missing?

You are missing to NOT use the evil DynamicDataType (DDT), that comes from using ExpressVIs like the DAQAssistent!

Which function should I take? 

Use plain DAQmx functions, they are really easy to use!

[dtfall]

I assume you're looking for something like this, where your signal of 25 channels is dynamic data which should be converted to an array using Convert from Dynamic Data express VI, and then you can apply your polynomial to each individual row/signal.

[Bob_Schor]

If you are having problems with something in your code and want help, it really helps those of us who lack telepathy to "show us the code" (which means "attach your VI") [warning -- if you attach a static picture, I, and others, will complain!].  

From some of the words you are using, I'm guessing that you are using Dynamic Data Wires, which many of us dislike (because it "looks like a single, simple thing", but has all kinds of mysterious features build inside it).  In general, when you ask DAQmx to sample N channels, of course it gives you the output in an array of some form (again, the form of the array depends on the details of the DAQmx Read function, which is another reason to "see the code" so we know precisely what you did).

Suppose you know how to take a single channel and operate on it with your polynomial.  If you now have an array of channels, you simply bring your array into a For Loop (where it will, by default, create an indexing tunnel), you can operate on the (single) element with your polynomial, then bring the output out through another indexing tunnel, resulting in an array of results.

Bob Schor