Time delay separate to while loop

[JohnGreen]

How would I be able to obtain data (pressure read in by DAQmx) that happened 2 seconds previous?

I need to obtain the pressure difference from 2 seconds ago hence need the previous pressure with a 2 second time delay. When I try and do this the whole program delays by 2 seconds, even when I try separate the time delay through use of another time loop. 

Any suggestions?

[Yamaeda]

Sample every second and use the 2nd from last sample?

/Y

[JohnGreen]

Excuse my stupidity but how would I get the second from last sample?

[apok]