Having Trouble creating XY Graph

[edmiles55]

I am trying to create an I vs V curve. The voltage comes out of a function generator outside a For Loop and the current comes from inside the loop. I have pulled the y data from both and need to place the voltage data on the bottom but get no response from the XY graph.

[Caseyw]

I would suggest looking at the data coming out of the function generator and the data coming out of the loop as well to make sure that they are both valid arrays. After that, you can use the "Bundle" function on the clusters pallette followed by the "Build Array" function on the arrays pallette. The data coming out of the build array function can then be wired to the x-y graph.

I hope this helps. Please let me know if you need more help on this issue.

Casey Weltzin

National Instruments

[edmiles55]

Both of the function generator and the output data look like they should except that the function generator is a static display. It provides one second of data, and then freezes. The time display shows 7:00pm 12/31/1903. I have been told that this means that there is no time data but am unsure how to correct.

[Caseyw]

What are you using to generate the "function generator" signal? Are you taking a measurement from actual hardware or just simulating a signal? In either case, is the data coming out as a waveform data type or an array? I think that once we figure out these issues we will be able to find a solution.

Casey Weltzin

National Instruments

[edmiles55]

The function generator here is a simulation outputing a sine wave to circuitry and the mearsurement is the current responce from that circuitry. The data comes out of the frequency generator as a waveform but then put through a Get Waveform Compnets VI and read by the XY graph. The measured signal comes from a DAQmx read and is converted in the same way.

[Caseyw]

It sounds like all of your data types are correct, and that the data acquisition is not generating and sampling your signals correctly. You mentioned earlier that the function generator shows one second of data and then freezes.

Please run your VI for a few seconds and then look at the number of samples in both arrays you are attempting to wire into the X-Y graph. Both of them should be roughly the same size. It sounds as if your function generator output stops generating data too soon and so the graph doesn't come out correctly.

Let me know how this goes, and if necessary attach the problem section of your code. I'm sure we can work through this and find a solution.

Casey Weltzin

National Instruments

[edmiles55]

You were right they were very different. The function generator has 1000 array elements while the signal has only 158. I will attach the lab view design I have. I am new to lab view, less then a week, so if you could keep taking me through your thought process it would be great. I really want to understand this software.

[Caseyw]

At this point, I think that once your application correctly generates synchronized analog output and input data you will be up and running. The LabVIEW Example Finder actually shows exactly how to do this. Go to help, find examples to open up the example finder and then navigate to the daqmx, multi function, multi function synch AI AO example. I think this should help. Also, a lot of the other examples available here may be helpful depending on exactly how you want to generate and acquire samples.

Please keep in mind that in order to view these examples you will have to have DAQmx installed.

You might also want to think about generating and acquiring a set number of samples vs. continually acquiring as your code currently shows. If you wish to output 1000 points for example, and input the current after each voltage is outputted, then you are really talking about a finite (N-sample) acquisition. If it turns out that the finite acquisition is what you want, you will have to decide if the acquisition needs to be retriggerable or not as well.

I hope this helps.

Casey Weltzin

National Instruments

[Ayuda]

hello edmiles55 I'm Mauro I'm Ecuador adn I have a trouble with my tesis I need perform a data adquisition of two sensors for a tracion test

I am making my thesis project with two sensors just as your please can  to lend your final program to me of acquisition because he is equal to the program that I need sorry by my english I only speak spanish ..... you are my last hope please help me att

Mauro

[Ayuda]

hello I'M Mauro agan this is my mail dinnnky12@yahoo.es send me your help