OPC Foundation
The home of OPC specifications
OPC Programmers' Connection
One of the best site on the Internet for OPC developers
OPC Multimedia Tutorial
Excellent OPC tutorial from Matrikon, requires Macromedia Flash Player
OPC Book
All you want to know about OPC
AutomationMedia.com
Controls and Automation Knowledge base, QA Forum, News, Articles & lots more…
Codegear
The home of Delphi and C++ Builder
