What does "reg the fault diagnosis" mean?
Some issues I see with your VI is that you have some controls with meaningless names. What do "Boolean" and "Boolean 2" do?
When I boil down your message, I would summarize it that you have problems getting data in "real time" mode. I imagine that is the case where the VISA data is read.
What I see there is that you have an inner most while loop that collects data from the serial port, it plots it to varies charts. And that loop will continue until you either hit one particular Stop button, or you get a VISA error. All of your code outside that while loop and in your other cases will never run due to data flow, until you stop collecting data, and when that happens, only the last acquired data will come out of the loop.
