Hi, K C. In another post I got some examples. In my case , I have a data source which outputs two numbers at a time(like 8.2 9.6), then after a fixed time interval, it outputs another two numbers...... I want to keep these numbers in a two demention array. I attach a example(add to array.JPG) from someone(in another post you can find the details) which has a fault , that is if two same number come along, it can only save one to the array. I attach another image of vi which I made myself(add to array[1].JPG), which has a fault too, I didn't know why, wish you can help me. Tomorrow I will go out for several days. So I cann't reply in the following days.