single data point from trigger event PCI-6115

[MilosMania]

I am trying to trigger off or a zero crossing from (approximately) a sinusoid. The sinusoid is a bit noisy, so I am using a hysteresis level. The sinusoid is about 27kHz, and the PCI-6115 can sample at 10MS/s. When a trigger event occurs, I want to take 1 data point which needs to be stored in memory and later written to disk after the entire acquisition of many data points is over. The entire acquisition lasts approximately 10 seconds. 

I've attached my vi showing how I am trying to do this. It seems like the triggering and single data acquisition can't keep up with the sinusoid. Any thoughts on what's going wrong? 

[_Tim]

Your DAQmx Start Task and DAQmx Start Task should be moved outside of the while loop. In your current configuration, you are starting and stopping the task every time you iterate through the loop. There are examples in the LabVIEW Example Finder that are great for helping to set up DAQmx tasks.

If that doesn’t solve the issue, what type of behavior are you seeing from the program?