How to set default value and after that , use it as control

Hello,
Currently i am making motor driver from labview, and i am facing one problem.
When i connect to my board via labview, it will relay last position to global variable. After that, i have to go to loop, where i can send back  modified position to my motor control board
In short, i have to control number, but that number default value should be writtem by another function when i start vi.

any ideas how to do it ?