Your VI will run forever because you have a False constant wired to the stop terminal of the loop.
Why do you have a while loop in there anyway?
You don't have any element going into your replace array subset. So you have a broken arrow.
I don't understand the meaning of your buffer full boolean. It really isn't telling whether your buffer is full or not. It doesn't even track how many times you've replaced various elements in the array. It just checks whether the value you used for index is a multiple of your buffer size. Let's say yor buffer size is 10. If you use an index 9, the remainder of 9 mod 10 is 9, it's not equal to 0, so the boolean is false. Okay.
Now if your index is 10, 10 mod 10 is 0, it's equal to 0, so the boolean is true. Okay.
Now if your index is 11 (obviously bigger than 10) 11 mod 10 is 1. It's not equal to 0, so the boolean is back to false. But is seems like you really intend for it to be true.
You aren't really ever checking if your array is "full". You are just comparing your entered index to your "buffer size" input, which may not actually have anything to do with the size of the array.
