[RESOLVED] Siemen's OPC, WinCC, Tags, Allen Bradley Products

What do these things have in common? I'm not quite sure, but I have to find out.

I work for a series of grain elevators and one of the things we have is a PLC Monitor that uses WinCC. We're adding in a new "component" to the elevator (it's a big bin that holds the corn) that monitors how much grain we have distributed. This is supposed to change every 40 seconds, but it's my applications responsibility to monitor the tag and grab the new data.

The problem is, I can't find an SDK or any developer documentation for this. And the only tool at my disposal is VS.Net 2003 and anything I can find that's free. Literally, the only knowledge that was passed to me was from the person who creates the interfaces with WinCC. All he told me was "well... I can find it here" and he pointed to a listbox on a form in his IDE.

Has anyone delt with Siemen's OPC or WinCC? If so, please point me to some kind of a resource about how these things work. The only material I can find is marketing propoganda about what it can do.

Edit: Sorry about the broad, generalized question. I just literally don't know enough about this stuff to formulate a decent question.

(almost forgot)
Edit2: My job is on the line, please help! :)