Triggering off of a digital waveform

[Moor]

Hello,

We are using Labview to generate and triangle wave to control a galvo, but would also like to use this waveform to trigger scanning/measurement functions and data-saving functions as part of the duty cycle of the program.  We're interfacing with our instruments via NC PCI-6115 DAQ card and BNC-2110 Connector Block.  We don't need for this cycle to go remarkably fast, but we do need our method of triggering to be precise.

I'm not very experienced with LabView, do you have any recommendations for a method of internally triggering from a LabView-generated wave?

Please let me know if there are any useful specifics that I've omitted.

Thanks,
Moor

[Moor]

Also, I'd like to load this waveform into the DAQ buffer, so my trigger will need to be able to trigger off of that.  

[mallorim]

Hi Moor,

In order to provide a knowledgeable solution to your problem, it will help if you first answer some questions:

1)     What are the parameters of your triangle waveform: frequency, amplitude, etc? Will this change on the fly or will you use on-board regeneration to simply repeat periods?

2)     What do you mean by trigger scanning/measurement functions? Do you mean that you will have some analog input that you would like to read once every period of the triangle wave?

3)     What did you mean by data saving functions? Are you interested in writing your data to some sort of file as you go?

There a number of example programs that you can look at in the NI Example Finder for writing data to a file and for voltage generation.

The two best ways to trigger analog measurements are going to be:

1)     Analog Triggering: Wiring the triangle waveform signal into an analog input and using the 6115’s analog triggering capabilities. This means that you can trigger when the waveform passes a voltage, either rising or falling. However, this can get complicated.

2)     Post-processing: This is most likely the easiest way. This will involve your analog output and analog inputs sharing a start trigger and a sample clock. You will continuously be reading the voltage measurements, then you can decimate, or throw out, all the data points that you do not need.

   Hope this helps, Mallori M.