Record a signal for arbitrary amount of time?

[nwinter4456]

Hi all,

I have a small circuit that acts as a "piano" (different voltages are sent into a small 8 ohm speaker, which then plays the signal). 

My problem that I've been working on is that I would like to record the voltages that are being sent through the speaker for some arbitrary amount of time -- until the user presses a button on the front panel. To do this, I've thrown a DAQ express VI inside of a while loop, and have set the VI to "1 sample on demand" -- every iteration of the loop, the DAQ picks up 1 sample, and appends it to an array. This repeats every iteration of the loop (the stop condition of the loop is set by a . 

However, the loop doesn't appear to iterate fast enough (the signal comes out very messy). Continuous sampling would appear to be better, but I'm not sure how to do this for some arbitrary amount of time, until a button is pressed. I would appreciate any suggestions on how to accomplish this.

Once the "stop" button is pressed I'd ideally have an array of doubles containing all the voltages recorded, which I can then go on to manipulate...

Sorry if this is a very easy question -- I'm super new to LabView!

[crossrulz]

1.  You definitely want the continuous sampling.

2. You really should not be appending data to an array.  That gets memory intensive to constantly reallocate arrays each iteration.  Instead, use a Producer/Consumer to use another loop to stream the data to a file.