Based on your description, I am not sure if this is exactly what you need but I created an example of using a single stop button and a local variable in order to stop 2 while loops simultaneously. In one loop I am just getting the current time and in the other I am generating a simulated signal and displaying it. Is this what you are looking for?
(I will include the VI in LV 7.1 as well as a screenshot in case you have an older version of LV)
-scraggs99