Sorry for the long delay. Most of the company is on vacation last week and we are trying to get things out the door for NI Week. My apologies.
The VI you posted will never change its outputs because the input data to the analysis in the loop is static. However, after looking at some of your actual data, I think a simple peak detection will cause you problems. This is due to the fact that your signals are complex and not all the same amplitude. This results in some of the minor peaks on the larger signals being about the same size as the major peaks on the smaller signals. While you may be able to tweak the threshold to get a good signal, it is a very brittle solution that will not work reliably.
To solve this, use a cross correlation function with a representative pulse to "prefilter" the data. Then run a peak detector. Information on correlation functions can be found in most statistics books and in
Numerical Recipes in C, by Press et. al.
You can make your posted code "work" by changing the WHILE loop to a FOR loop (right click on the loop and select "replace with FOR loop") and wiring the 2D array directly into the peak detect VI, using autoindexing at the loop boundary (default behavior). This will cycle through your data and give you a changing output. In a real-time environment, you would keep the WHILE loop and put your data acquisition block inside it. You will probably need to deal with half-pulses showing up on the edges of your data. Shift registers are your friend in solving this issue.
Note that your dt and sampling rate inputs are simple inverses of each other, so you only need one of them. In addition, you have a lot of redundancy in the FOR loop and top code paths. These could be combined into a single FOR loop fairly easily.
Finally, you might try searching these forums for other examples of this type. For example,
Analysis of ECG Signal may have something of interest. As that thread says, heart beat analysis is not trivial. Good luck.
Message Edited by Support on 03-16-2009 09:41 AM
