access to data in another file

the folowing callback function is created in a seperated file, how can have access to the value of the toggle button i have created in other file tb is the name of the button

 function display_button_value(hObject,callbackdata)

    button_state = get(handles.tb,'Value');

    if button_state == get(hObject,'Max')
        set(findobj('type','line','Color','y'),'Visible','off')

    elseif button_state == get(hObject,'Min')
     set(findobj('type','line','Color','y'),'Visible','on')
    end

 end