What does the 'IUnknown' activex interface mean?

[Paul@BSH]

Hello everyone,

I am trying to use a program as an ActiveX server and have LabView (version 8.6.1 on Windows XP) be the ActiveX client so that I can query for information. When I use that automation open vi - I can see the object that I want to use like this:

So the refnum that is created is called 'PDMUNIVERSALCLIENTlib.IUnknown' and then when I try to select a property or method there appears to be nothing there, like this:

 

I have read what I can find about IUnknown - but it is still not clear to me what this means. Is there a way to get to the properties for this interface? Does IUnknown simply mean there is no ActiveX interface available to me?

I'd appreciate any insight anyone might have - Paul

[muks]

Iunknown

[Paul@BSH]

Thanks, Muks - But I have already read that tutorial and I still don't see how to get from 'IUnknown' to 'IUnknown:QureyInterface' in LabView. There doesn't seem to be any methods or properties that I can call from IUnknow as I stated below. I've searched for examples and can't see anywhere where others have used LabView to get to properties from IUnknown. Just wondering if anyone can show me how this can be done in case I'm just missing something.

[JeffL]

Hi Paul,

The equivalent in LabVIEW for QueryInterface is Variant to Data: http://zone.ni.com/reference/en-XX/help/371361F-01/glang/variant_to_data/

You can see a similar discussion here: http://forums.ni.com/ni/board/message?board.id=170&thread.id=254237