04-30-2009 04:56 PM
Hi,
I have a USB-6215 DAQ which I would like to use as a basic function generator regulated by a trigger signal. The trigger is generated externally, and has a rising and falling edge. Is there a way to initiate the output of my signal from the DAQ on the rising edge and terminate it on the falling edge? Essentially, I just want to have my trigger dictate the end of the output as well as the start. I've mucked around in SignalExpress for a while now, but only see options to initiate signal generation upon triggering; I can't locate anything that would terminate it. I'm quite new to SignalExpress and LabView, so this may actually be very easy to do. Can anyone help me out?
Thanks!
Nick
05-01-2009 08:34 AM
Hi Nick,
I don't think that you can actually perform this type of generation with SignalExpress, since it is basically like using the DAQ Assistant in LabVIEW. There is a limited amount of functionality that you can get from that. If you have LabVIEW, you could do this using a pause trigger that is set to pause when low. This way, you can make sure to start your task before you send the start/stop signal so the AO task is waiting for that signal. Once the board receives the rising edge of that signal, your AO would start and then when the the board sees the falling edge, it would pause the generation. From there you can simply stop your VI, so that you don't get any re-generation.
If you have LabVIEW, this can work. I would take a look at the LabVIEW example VI called Cont Gen Voltage Wfm-Int Clk-Pause Trigger.vi. You can find this in the example finder by going to the folder Hardware Input and Output>>DAQmx>>Analog Generation>>Voltage.
Chris
05-05-2009 01:04 PM
Hi Chris,
I do have LabView 8.5, so this sounds promising, although I can't locate the example file that you mentioned. Is there some place online it can be found?
Nick
05-05-2009 01:13 PM
Hi Nick,
You likely didn't install DAQmx support for LabVIEW when you installed the DAQmx driver. This is no big deal, you just have to re-install it and make sure that it installs support for LV 8.5 (you will see this option in the install menus). Then you should find that example program.
Chris
05-13-2009 07:35 PM
Hi again,
Sorry for this delayed response, but I have just had a look for this .vi file and can't locate it. I made sure that support for LV 8.5 (and the relevant examples) were installed, and did a search in the examples folder to no avail. I've been looking in the ...\National Instruments\LabView 8.5\examples folder with no luck. Any idea where I can locate it?
Thanks!
Nick
05-14-2009 10:14 AM
Nick,
I don't know why you wouldn't have this specific example, it may have something to do with what version of the DAQmx driver that you have. I have attached this example for LabVIEW 8.5. Hope this helps.
05-14-2009 10:32 AM
I was pointing you to a folder location within the NI Example Finder, which you can get to by going to Help>>Find Examples from within a LabVIEW VI. Thank you Aaron for posting the VI.
It is also available in the .llb file called Generate Voltage.llb, which is located in ...\National Instruments\LabVIEW 8.5\examples\DAQmx\Analog Out\Generate Voltage.llb, however, it is much easier to just use the Example Finder from within LabVIEW.
Chris
05-14-2009 12:36 PM