Mike, thanks for your answer, but I may not have explained things just right.
I'm trying to output an analog signal (the buffered sine wave) and, synchronized with it, a digital trigger signal (the counter). Their relative phase seems to vary with the frequency, so I can't just try to start them together. So I thought of taking the analog signal, feeding it into an analog input and using the analog trigger signal (ATCOUT) to start the counter.
I'm not sure what signals I should set to what values in Counter Set Attribute.vi to achieve this. The closest example is ATCOUT Viewer.vi found in Analog Trigger Circuitry Output as an External Signal.zip, but I don't need to use the double counter.
Thanks!