Detect pulse with USB 6009 DAQ and trigger shutters

[McBoris]

Hi i'm trying to detect a pulse generated by a wavefunction generator through the USB 6009 DAQ. Using MAX i can view the wavefunction (a Square function of 1Hz frequency and 2Vpp) however i don't know how to use labview to detect when this wavefunction goes above say 1V in order to then trigger a case event. Is the 6009 able to do this or do i need another DAQ device?

The wavfunction generator is connected to the anolog ports 2 and 3.

any help would be greatly appreciated. Thanks.

[Christian Mergl]

Hey,

You can use the LabVIEW Example Finder (help menu) to search for a triggered analog acquisition example.

However, the USB 6009 only supports a digital trigger on a rising or falling edge. There is no way to set a analog trigger with a certain voltage level.

Christian

[McBoris]

Thanks Christian that would make sense as i continually got error message's when trying to trigger on the rising analog edge.

Now to ask a very simple question, how do i setup the waveform input as a digital signal instead of the analog?

Thanks again.

[Christian Mergl]

A digital trigger has to be a TTL conform signal and needs to be connected at PFI0 of the USB 6009.

You should take care about not harm something of your device when connecting your signal which might not be withing the TTL specifications.

Christian

[McBoris]

Ok so i've connected my pulse waveform into the PF10 of the USB 6009. I can get it to count the pulses (using MAX) so i know that it's recieving the signal.

I now need to make the pulse detection (or edge detector counter) change a boolean varible so that i can get the shutters to start working. I can use the pulse to start an aqquisition of data through, say, the anolgue inputs of the 6009 and plot a graph of that input signal (like in some of the examples). But i don't need to do this, instead of triggering an aqquisition, can i use it to change a variable that can be used to start an event case?

Thanks

[AdnanZ]

Yes, you will need to dynamically register an event. Refer to labview\examples\general\dynamicevents.llb for more examples on this.

[McBoris]

Ok so i've been trying to use the register event to trigger my event structure when the value of the signal changes (ie when it counts an edge). I've attached a picture below. I can't seem to get the event loop starting though....any suggestions??? thanks.

[AdnanZ]

Counter output event is a signal produced by a counter when it reaches terminal count. I believe what you need is a change detection event which is a signal a DIO device generates after it detects a change on the data lines. Have a look at DAQmx Events and Digital Change Notification example for help.

[McBoris]

Thanks for your help. I understand what the example is showing. I just don't know how to change it for the PFI0 input as that example only works for the digital inputs...

thanks.

[AdnanZ]

When exactly do you want to trigger an event? On every rising edge or when the count reaches a certain value?