Hi, I am trying to clear up the string by clicking a button.
I attached a picture of the block diagram within this posting.
as you guys can see, I want to clear "read string" and "string to write", which are in the case structure.
However, though I click the button, the string doesn't go off.
Please help me out of this problem.
Hmm... it works for me. You do know that as soon as you clear the Read string, the serial read will populate it again. So it will appear to not clear. However, the write string should clear just fine.
Also, if the code is in the delay sequence, the strings will not clear until the delay is over because the code will not read your buttons until the delay is done.
Attach your entire vi and any subvi's that it calls. I see nothing wrong with your picture.
It works just fine for me.
If you are still having problems, try running your VI with highlight execution turned on to see how it is executing. Maybe put a Beep VI inside that case structure so you can hear that the case is executing.
Perhaps that's the problem: Your buttons have switching behaviour and your cases are wired to be executed on button press (true) so clearing the strings only works when pressing a button, not when releasing it! I'd suggest to use latching buttons and an event structure.