topic Re: reading from an array in LabVIEW

reading from an array

arabic — Mon, 14 Jan 2013 20:57:18 GMT

Hi everyone,

i have read a .txt file (printed from matlab as table) into labview as array indicator.

i used array index to send the values from the array to their outputs, like some values connected to DAQ as voltage output, some sent to indicators to just show the value on the GUI some are sent to xy graph to be ploted.

however, the DAQ does not really read the value because the intensity of the LEDs dont really change with changing the value.

the second problem for the xy graph i used the buddle to connect two array indices as x and y and when i connected the buddle to the xy graph it shows diconnected line 😞

any solutions or what is that happening?

thanks in advance 🙂

Re: reading from an array

altenbach — Mon, 14 Jan 2013 21:14:14 GMT

Then please show us your code. We cannot tell what's wrong from your description.

(Also, are you talking about "bundle" when you say "buddle"?)

When you bundle data for an xy grap, it wants e.g. bundle of two arrays or an array of xy points or a complex 1D array. If you only blndle two array indices, there is no array.

Re: reading from an array

arabic — Mon, 14 Jan 2013 21:21:49 GMT

here is my block diagram. and yeah i mean bundle sorry!

thanks for the reply 🙂

Re: reading from an array

altenbach — Mon, 14 Jan 2013 23:21:29 GMT

No, we need to see the actual VI. pictures are useless.

As I said you are wiring what looks like a waveform graph to a cluster with two elements. Where's the xy graph you mentioned earlier. Maybe you want to use a chart?

What is the point of the sequence frame?

Index array is resizeable, all you need is a single instance, not eleven.

What's in the false case?

Why do your wires go in all directions?

Re: reading from an array

arabic — Tue, 15 Jan 2013 06:46:07 GMT

hi sorry for the late reply

here is the file

no im ploting points not waveform graph

for each time i change the row number another value of x and a value of y will appear of the color space picture, the points represent the CCT values. i didnt manage yet to make the color space diagram as background of xy graph ( maybe you could help me in that too.) but later these points will indicate to the user which CCT the light spectrum is he/she using.

i couldnt import more than 3 files, in my next reply i will put explaination on the block diagram and the GUI so you understand what im trying to do.

when you run the program please upload the text file you have. and the meaning of each column is shown in the picture attached bellow. please wait for my next reply

thanks

Re: reading from an array

arabic — Tue, 15 Jan 2013 07:07:28 GMT

here is the explaination

hope they are clear

thanks alot!

Re: reading from an array

altenbach — Tue, 15 Jan 2013 07:58:16 GMT

You definitly currently use a waveform graph (even if you label the axes x and y 🐵 First you need to replace with an xy graph, which is very different in datatype.

Do you want to add one xy point whenever you look at a new spectrum or do you want to graph all points (one for each spectrum) at once? That would be easier. If you want to add one point at a time, the "build xy graph express VI" set to "not clear data between calls" is the easiest solution. Otherwise you need to append the new point to an existing array of points kept in a shift register.

Also note that sliders have a digital display (right-click...show digital display) so you only need one terminal.

Here's a quick rewrite that shows ...

how to use index array more efficiently
How to use an event structure to prevent constant spinning of the loop (Your false case definitely would need a small wait).
how to display the digital display of sliders
How to graph all xy data at once
How to incrementally build the xy graph using a shift register
How to incrementally build the xy graph using a express VI.
I don't have DAQ, so I commented them out.

Re: reading from an array

arabic — Tue, 15 Jan 2013 08:54:58 GMT

im very new on labview so excuse my bad knowledge.

thank you so much this is what i wanted one point at the time and keep the point

one last question how can i change their colors and set a legend showing which set this point represent? ( the sent number is the same as the spectrum number).

by the way do you know how can i place that color space diagram as a background to the xy graph?

thanks so much!! 😄

Re: reading from an array

altenbach — Tue, 15 Jan 2013 08:57:17 GMT

A plot can only have one color, you would need to create N different plots and define their color. As a simpler alternative, I would recommend mapping the data into an intensity graph instead.

Re: reading from an array

arabic — Tue, 15 Jan 2013 09:01:17 GMT

i will work on that thanks alot!

what about the image? i saw examples online but i couldnt find the elements hahah thats why im lost 😞

Re: reading from an array

altenbach — Tue, 15 Jan 2013 09:26:12 GMT

Yes, you could use an image. for the graph. You could first plot the image and then the dots over it.

You need to place a 2D picture and use picture tools to compose the graph. Have a look at some of the examples (e.g. "xy multiplot" or "waveform and xy plots").

To place an image in the back of the xy graph, you can use the plot images tools. Have a look at the "plot images" example).

Re: reading from an array

arabic — Tue, 15 Jan 2013 09:39:35 GMT

i have found this and i followed the steps but still does not work :S

http://digital.ni.com/public.nsf/allkb/FF55BDA8C9F0C0ED862573450053A425

Re: reading from an array

altenbach — Tue, 15 Jan 2013 15:32:08 GMT

Then show us your code again....

Re: reading from an array

arabic — Tue, 15 Jan 2013 16:17:14 GMT

I have managed to do that!

two more remaining problems that i cant find solutions

first after ploting the points and displaying the values in the control box i want to reset everything how to do that?

and second i want to plot the spectrum using matlab code into labview how to do that?

if you help me in these two im done 😄

Re: reading from an array

altenbach — Tue, 15 Jan 2013 16:56:15 GMT

arabic wrote:
first after ploting the points and displaying the values in the control box i want to reset everything how to do that?

Create an event for the reset button and set the array containing the points back to zero lenght. What elese should the reset button do?

arabic wrote:
and second i want to plot the spectrum using matlab code into labview how to do that?

What is so special about matlab code? What does it do?

You can translate the matlab code into plain LabVIEW, probably with little effort. (preferred)

If you have mathscript, you can use matlab-like syntax without the need of having matlab.

If you have matlab installed, you can also use the matlab script node.

Re: reading from an array

arabic — Tue, 15 Jan 2013 17:00:11 GMT

the code is very simple im just going to plot the spectrum,

im going to try your suggestions and see which one works. if you have better idea for the following code please let me know 🙂

% Input Parameters

%peak wavelength

lamb1=468;

lamb2=570;

lamb3=689;

lamb4=700;

lamb5=0;

%intensity

i1=0.62;

i2=0.55;

i3=0.52;

i4=0.5;

i5=0;

light=gausslight(lamb1,i1,lamb2,i2,lamb3,i3,lamb4,i4,lamb5,i5);

plot(380:5:780,light,'b','linewidth',2)

grid on;

title('Light Spectra')

xlabel('Wavelength (nm)');

ylabel('Intensity')

the reset button should clear the graphs too.. :D

arabic — Tue, 15 Jan 2013 17:01:32 GMT

the reset button should clear the graphs too.. 😄