There are a number of ways to do this but the problem is going to be estimating how many samples are in a second. If you are using one of NI's daq cards, you can simply use the scan rate for this estimate.
To do the averaging, you can output an array of data containing all the points read for one second. Then you index the array to make several 1 d arrays. Then use the add array elements found in functions >> numeric palette to add the values and then divide by the number of elements.
