1. For your DI sample clock, try using "Ctr0InternalOutput" instead of "Ctr0SampleClock".
2. Assuming your external device is looking for the leading edge of the pulses you make, configure your DI task to be senstive to the trailing edge. Maybe you can make your pulses less square shaped to allow more response time?
3. Your DI start trigger probably won't work, and you don't need it anyway. As long as your DI task starts before your pulse generation task, it won't start sampling until the pulses show up.
4. I'd be wary of specifying the generic "OnboardClock" while defining pulses with Ticks. If you want to use Ticks, be sure you also explicitly select a known timebase. Or you can specify the pulses in terms of time and set units=seconds. That will also make clear what your nominal sample rate is for your DI task.
-Kevin P
CAUTION! New LabVIEW adopters -- it's too late for me, but you *can* save yourself. The new subscription policy for LabVIEW puts NI's hand in your wallet for the rest of your working life. Are you sure you're *that* dedicated to LabVIEW? (Summary of my reasons in this post, part of a voluminous thread of mostly complaints starting here).