how can i use control reference to pass integer to a sub VI
In your subVI (Sous3.vi), create a Numeric control on the front panel.
Right-click on the numeric and choose "Representation >> I32."
Ctrl-drag this numeric onto both the "Number In Refnum" and "Number
Out Refnum." This will change them to integer control references.
Note that you should change your top-level VI (Principal.vi) to pass
only integer control refnums to Sous3.vi.