I don't know if this is the solution that works for you, but here is one way.  You can place a generic refnum control [Controls Palette>>>Refnum>>>Control Refnum] on your subVI's front panel, and wire that into the "type" input of the Variant to Data function [Functions Palette>>>Advanced>>>DataManipulation>>>Variant>>>Variant to Data].  This will convert the variant back to a refnum.  From there, you can use a property node [Functions Palette>>>Communication>>ActiveX>>Property Node] and look at, for example, the ClassID property.  This will return a U32 representing the control type.  Watch out if at some point you convert the specific control reference to a more generic reference because you may lose the ClassID value.
Message Edited by boomer on 07-10-2007 03:28 PM