Pass continuous discrete averages out of loop

Question

Hi,
I have a DAQ that's acquiring 1 sample at 1 Hz. I am trying to get the program to continuously acquire samples but to output the average of every 10 samples, which I use at a later point in the program for calculations. I have found a lot of topics on the NI forums that discuss running averages but this is not what I am looking for. I have also found this link that shows a labview program that can acquire a given number of samples, average them and write to a file (2nd diagram from the top). This is very similar to what I need except for the part where it displays the mean within the case structure.
http://forums.ni.com/t5/LabVIEW/How-to-make-labview-program-to-get-average-value-of-200-reading/td-p...
I am able to write the averages to a file or display them within the loop. However, I need to pass the average of every 10 samples out of the loop. In other words, the DAQ acquires continuously but at the end of every 10 seconds, the algorithm outputs the average of the data from those 10 seconds. Can anyone tell me if this is possible in Labview 2010 and what function will help me achieve this?
Thanks for reading!
av10

Answer 1

You are very close.  Look at your Consumer loop -- you dequeue one element from the Queue, then pass it into a "Do Forever" loop that shows the single value.  Put the Dequeue also inside the loop, and you'll have what you want.
The Producer loop will continue to put Means on the Queue.  The Queue "wire" is a bit unusual in that data can pass "backwards" through the wire (it doesn't really -- the wire just identifies a conduit in which the data travels).  Once the data is on the Queue, any Dequeue element (like the one you will move into the Consumer loop) will have access to the "conduit" and will be able to remove the data and do whatever you want with it (like display it on the Numeric indicator -- consider renaming that something more mnemonic, like "Mean Value").
One question that comes up with multiple loops is How Do I Shut Them All Down?  Here, again, Queues are your Friends.  Inside the Consumer Loop, wire the output of the Error Line coming from the Dequeue to the Stop indicator (this Consumer loop is so simple you don't need to worry about an Error Case statement).  When you Release the Queue after exiting the Producer Loop (in response to pushing the Stop control), the Queue itself will disappear, and the Dequeue function in the Consumer Loop, which is waiting for a new value, will instead throw an error.  Well, this error you will interpret as "The Queue Is Dead, Time to Stop Consuming", and by wiring the Error Line to the Consumer's Stop terminal, this will stop the second loop, and your program will exit.
Let us know if this answers your questions, and solves the problem you were raising.
BS