Can I gate analog output with digital input?

[flomby]

I am using the USB-6259 board with NI-DAQmx in .NET.  I need to gate several analog outputs with a digital input.  I want all AO signals at zero until the DI goes low.  Then the AO signals should be set to some pre-determined level.  When the DI goes high the AO signals should go back to zero.  Is this possible without any external hardware?

[MickeyD]

Hi Flomby,

Your application sounds like it would best be implemented using a pause trigger.  You can find information about what a pause trigger is in the DAQmx Help.  If you need help with the C function calls you can find that information in the NI-DAQmx C reference help.  I would recommend searching for Pause trigger in both of those help documents and working your way from there. 

There is also an example program for using a pause trigger to control an analog input, but you could change that task to an analog output.

DAQmx - AI with Analog Pause Trigger

Please let me know if you have further questions dealing with this issue.

Have a great day,

Michael

[MickeyD]

Hi Flomby,

I apologize, but the example program from above was designed to use an Analog Pause trigger, which is not quite the functionality you are looking for.  I would suggest looking at the reference help as well as this link, which describes several triggering applications using NI DAQmx the graphics are taken from LabVIEW, but the function calls should be made in the same order.  Sorry for the confusion.

Tips and Techniques in Data Acquisition Triggering - NI-DAQmx

Have another great day,

Michael

[flomby]

Michael,

Thanks for the reply.  I have implemented the pause trigger, but it doesn't seem to be quite what I need.  I need the AO channel to go back to zero at the end of the digital pulse and the width of the pulse can vary.  Is this possible?

[MickeyD]

Hi Flomby,

I was thinking about your application further, and am still considering the best way to try and implement that with hardware timing.  I was just going to ask how precise does the AO need to follow the change of the digital input.  Does it need to instantaneously change, or could a transition time of as high as a millisecond be acceptable.  I see why a pause trigger is not providing the functionality you want, but we could do this in software if that would be an option.  I will get back to you about a straight hardware logic option, but let me know if a software option with longer transition times would be an option.

Have a great afternoon,

Michael

[flomby]

Michael,

I was hoping to use a hardware solution, but 1 millisecond software solution might do the trick.  I have been unable to achieve that quick of a response with software.  Do you have a recommended approach?

Thanks,
Flomby

Message Edited by flomby on 11-15-2006 11:14 AM