how to send a pulse signal with specific frequency with PXI-5412

[cbing8859]

Hi,

This might be a silly question since I'm still new to Labview...

I'm trying to control a PXI-5412 function generator to send a pulse signal (say 10 cycles, repetion time 10ms) to our ultrasound transducer. I need to assign a specific frequency to the sine wave I generate (like 1.055MHz). I assumed that I should use the arbitrary sequence waveform in the output mode, then generate a waveform combined with a sine wave and a period of DC, then make the loop count to 10, so I can get the pulse signal. 

I checked the examples in NI called "Basic Arb Sequence", which can do what I want, however, the way they design the signal is by # of points, not frequency... the vi called "Sine Wave [NI_AALBase.lvlib]" has two control terminals: # of points and frequency, I don't know how this work...

So, my question is, can anyone help me figure out how to assign a specific frequency to the signal when I use the arbitrary sequence waveform to generate a pulse signal? or is there any other way can complete this task??

Thanks!

[Wayne_T]

Hi.

Looks like the sample rate would be set using niFgen Set Sample Rate.vi.  In my LV 2013, this VI is located in Functions >> Instrument I/O >> Instrument Drivers >> NI-FGEN >> Configuration >> Clock >> Configure Clock >> niFgen Set Sample Rate.vi.  Also, review the help documentation for this function to see how it is used.

[cbing8859]

Hi Wayne,

Thanks for the reply. Actually I just figured out a way to do this. I used anohter sine wave generator vi to control the frequency instead of the one they use in the NI example. It worked. However, I here have another question..

The signal I generate with PXI-5412 was not quite stable... It kept jumping from here and there... Sorry I don't know the professional way to say this but I think you can get my point. I thought there might be something I can work on for the trigger, but I'm not sure.. Any suggestion on this will be helpful. Thanks for your time!!

[Wayne_T]

cbing8859,

Is there any difference in stability if you just add the niFgen Set Sample Rate.vi to your code?  That way only the ability to change sample rates is added, nothing else.

[cbing8859]

Wayne,

It didn't change.. the signal was still unstable...when I set the oscilliscope to autoset, the signal worked just fine, however, when I change to trigger mode, the signal starts to jumping.. I think there's something wrong with the trigger... Do you have any suggestion on that? Thanks!

cbing

[Wayne_T]

cbing,

Can you provide information on how the trigger mode and the trigger source is configured?  What type of trigger are you using, software edge, digital edge?

[cbing8859]

Wayne,

Thanks for the reply. I thought I figured out how to solve the problem ... after I adjust the signal from the oscilliscope, it looks right.. thank you for helping this out, I appreciate it!

cbing