If I understand correctly what you're saying, there is a gap in you data when you click on the graph, or zoom in on it. If you have the acquisition and the graph in the same loop, you could be essentially pausing or slowing down the loop while you are interacting with the graph. I've never noticed this effect before myself, but it is possible.One solution might be to put the acquisition process in a seperate loop and pass data to the loop containing the graph in something like a queue.Mike...