How do I pass a COM-Port (s) to and from other GUIs (GUIDE)

Hello *, I have the Problem when running MATLAB on Windows it takes for ever to request a COM-Port. I would like to request it only once and then pass it or Access it through other GUIs created by GUIDE. I managed to pass s [ =serial(strcat('COM', num2str( state.com_popup ))) ] through functions within a GUI or .mat file. But I would also like to pass it to children or get it from the parent. I have one master GUI, opening several other GUIs operating different things on ONE COM-Port. I tried something like: handles.s = serial(......) fopen(s); guidata(hObject, handles);

But I do not reach the parent where I did fopen(s).

I was able to see how to pass between "figures" but not between the main GUI and others. get(0) -> and so on but I did not find my open COM-Port

I guess I Need help.