How can I record data at exact 0s,1s, 2s

[MYLONG]

I like to acquire data at controlled rate, I hope time is 0s,1s,2s, 

I attached the code. I knew I may need to use elaspsed time to determine if elspsed time is 1s every loop.

But I tried, it does not work

Who can help me out please?

[sparkysquared]

I think you're making this much more complicated than you need to. Just use a wait of 1000ms. Also, I noticed you hadn't initialized your boolean shift register to false. If you don't, then the second time (and every other time) you run this program without closing it first it's going to start acquiring data before you hit acquire. See the changes I made.

--Ryan