• Specifications: OPC Data Access 1.0, 2.0 and 3.0, OPC Alarms and Events 1.10 and earlier, OPC Universal Architecture (through UA COM Proxy - included).
• Tested for compliance with standards and interoperability.
• Supports operating systems from Windows XP, Windows Server 2003 to Windows Vista, Windows 7 and Windows Server 2008 R2.
• Multi-threaded, non-blocking design for high performance.
• Internal messaging layer provides isolation between OPC communications and the custom client code, resulting in high resiliency.
• Automatically connects to and disconnects from OPC Servers.
• Automatically adds, removes and maintains OPC groups and items.
• Conserves resources behind-the-scenes by automatically disposing of objects that are not being used.
• No limits to number of connections, subscriptions, or tags.
• Automatic server status checking, detection of connection problems and server failures, and automatic reconnects.
• Maintains client state and reconstructs the internal state of OPC server after reconnection.
• Supports all flavors of OPC synchronous and asynchronous reads and writes, subscriptions, browsing, and property access.
• Multiple independent OPC server connections.
• Intelligent OPC Group parameter optimization.

Leaflet

The code below (in C#) reads and displays an item value, using QuickOPC.NET:

// Read item value and display it in a message box MessageBox.Show(EasyDAClient.DefaultInstance.ReadItemValue("", "OPCLabs.KitServer.2",     "Demo.Single").ToString());

The code below subscribes to changes of an item, and displays the value with each change:

// The callback is a lambda expression that displays the value EasyDAClient.DefaultInstance.SubscribeItem(     "", "OPCLabs.KitServer.2", "Demo.Single", 1000,     (_, args) => Console.WriteLine(args.Vtq.Value));

No other product can do this in such a clear and concise code, in a single statement! 

The same code simplicity is maintained in other programming languages. Here are the corresponding examples in Visual Basic (VB.NET).