Output continuous digital waveform

[SurfaceSurfer]

hello,
 
I'm attempting to write a continuous digital waveform using the 6259.
I haven't had any luck but would like the duty cycle to be 50% and be able to vary the frequency over the range of the daq cards capabilities. I have been able to use a while loop but the waveforms frequency is too low and not as precise as we need. We're looking for frequencies >500kHz.
If anyone has any suggestions I'd appreciate it.
Also we're using Labview 8.0.
 
best
SS
 
 
 

[SurfaceSurfer]

Hello,
I've used the example "Gen Dig Pulse Train-Continuous" from the example library and it looks like it is working but the one thing that I'm unable to figure out at this time is how to have the VI running and be able to dynamically change the frequency value.
Does anyone have an idea on how to do this. I currently just use two boolean operators to stop the while loop, which then allows the parameters to update the next time the RUN buttton is pressed. Perhaps there is a better method of generating the continuous pulse train with this on the fly parameter changing ability.
any ideas would be appreciated.
thanks
SS


DIO_Continuous.jpg:
Loading Image...


gen Dig Pulse Train-Continuous.vi:
http://forums.ni.com/attachments/ni/70/8100/2/gen Dig Pulse Train-Continuous.vi

[Chris_K_]

Hi SS

Thank you for using our discussion forms.

You were on the right track.   Have a look at the VI that is attached.  It is the finite pulse train example that you have been using.  I just added a DAQmx Write (Counter Output) VI in the loop.  This allows you to update the task as it is running.

I have also added a Wait VI that uses the updated frequency as an input.&nbsp; You must ensure that the pulse period (in seconds) &lt; loop wait (in seconds) otherwise you will run into errors.&nbsp; For more information please see the following <a href="http://digital.ni.com/public.nsf/allkb/5F4D0C03B345468986256E85005A2FCC?OpenDocument" target="_blank">link</a>.

Have a great day

Chris_K

&nbsp;Message Edited by Chris_K_ on 01-25-2008 02:38 PM


Pulse Train with Digital Update1.vi:
http://forums.ni.com/attachments/ni/70/8103/1/Pulse Train with Digital Update1.vi

[SurfaceSurfer]

Hi Chris,
Could you post a JPG of the VI. I'm running 8.0 and it doesn't seem to want to open.
Thanks for the help in advance.
&nbsp;
best
SS

[Chris_K_]

Sorry about that, I meant to post an Image anyway.
Here you go.
<img src="Loading Image...">
Chris_KMessage Edited by Chris_K_ on 01-28-2008 10:49 AM


Pules Train with Variable Frequency.JPG:
http://forums.ni.com/attachments/ni/70/8113/1/Pules Train with Variable Frequency.JPG

[SurfaceSurfer]

Chris,
Just what I was looking to do. thanks again.
best,
SS