This appears to be a continuation of your thread from here: https://amibotted.comcast.net/authorized.html
However, reading that thread does not make things any clearer as to what you are asking. Your loop is talking to some serial device. What does a pulse have to do with this? Where is this pulse coming from? Are you generating it? Is the device you're talking to generating it? How are you supposed to measure it? Is that what you are trying to do with the serial command?
P.S. You already have a while loop in your VI, so you do not need to use "Run Continuously". That (poorly named) mode is the same as you pressing the Run button each time the VI stops.