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knifeman

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Posts posted by knifeman

  1. Merry charismas every friends!

    The question I post some days ago have been solved, and I am too busy to browse the Internet so make you spend your time and interesting on my topic, thank you. Thank you very much! Your hot passion make the winner become warm and hopeful!

    The point to solve the problem is to initial the loop structure. With the method the program could tell apart which is the content this loop and which is the last loop, otherwise it read every strings and do not analysis what is the useful part, and this is my question

  2. My OS is LabVIEW 8.0. I want to analysis the harmonic containing in a waveform which I get from the signal source through the DAQ card. It is all OK until the next step FFT!

    Signal source create a 50Hz, the amplitude is 1 square waveform and LabVIEW has received it successfully went with a error. The FFT result should be amplitude=1,dB=0 at the 50Hz point. The fact is amplitude=0.9040,dB=-0.8764 (I create a program to write the result in .mat format file and use Matlab to check it), and the front panel is given bellow. And the 061126_*.mat is the exactly data and

  3. Thank you everyone.

    chrisdavis and PJM, I am agreed with you so much,but I have no choice to select which card,and I can not change a new card for using now.So I have to deal with any problem of it. :( But still thank you for your help,thank you.

    crelf and Bryan,your advises are so excelent! I will try it, maybe the problem is solved tomorrow morning. :)

    And now, I use Call Library Function Node to build a DLL file completely and successfully,but LabVIEW noticed me when the VI is running. Some days before,I have read an artical which said the reason maybe is an interrupt is contained in DLL. I an not familiar with it,do you know about it? Could you tell me the more detailed information?

    Thank you!

  4. Thanks for chrisdavis' help and suggestion.

    NI DAQ card is much expensive than Advantech product, and I selected the Advantech PCI 1711,using the Windows 2000 and LabVIEW 8.0 platform, and I want to use VC++6.0 to write a program to drive my DAQ card.

    As you known, DAQmx only support NI cards, so I must write the drive program although Advantech has given the demos for common function such as AI,AO,DI,DO etc. But they have their disadvantages,especially they can not support more complex function.For example,use Timer to creat more precise signal. So I want to use C language to build my program to accomplish my purpose.

    OK,I will connect NI for more information.

    Thank you again,chrisdavis,thank you!

  5. post-6797-1163156640.jpg?width=400

    In LV8.0's example,there is a dome use the harmonic analysis.vi to analysis the harmonic distortion condition of a mix signal which components contains fundation frequency and 2rd,3rd harmonic.
    But I use the signal source to generate a 50Hz sine signal to input and use the same harmonic analysis.vi to get the harmonic information,and the error born! The frequency's range is form 0 to 0.6,and I do not know why. :headbang:

    Help and thank u very much!
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