Hi Nasser2
First I want to invite you that the next time the you have a new problem to open a new threat, because its difficult sometimes to answer the new problems in old threats. Be sure you will get a response when you creat a new threat.
Now about your problem. Here is a snippet that can help you to do it, replace the numeric controls with the singal of your daq assistant, and well you can't take out the while loop an just take the code inside of it and add it to your original code. This just will work the first time they goes down to zero bye each time you run the VI. You might need somo changes to make it work all the time.

Greetings
Julio