OPC development on COM platform

Microsoft COM (Component Object Model) is a Windows-specific technology that allows interoperability between programs written in different languages and tools. QuickOPC offers a set of COM (OLE Automation) component for COM client and subscriber development.

The components can be used from various languages and environments. The available examples show how the components can be used from Visual Basic (VB, VB6), C/C++, VBScript (e.g. in ASP/IIS, or Windows Script Host), JScript, Perl, PHP, Visual Basic for Applications (VBA, e.g. in Excel), Visual FoxPro (VFP), Delphi (Object Pascal), REAL Studio (REALbasic), Xbase (Xbase++), T-SQL (SQL Server), PowerBuilder (using PowerScript) and other tools. Any tool or language that supports COM Automation is supported.

Useful links: Documentation / Examples / Knowledge Base

OPC COM Code Sample (VB6)

QuickOPC is easy to use - here is a complete Visual Basic (VB6) example which reads and displays OPC data from an OPC Unified Architecture (OPC UA) server:

' Instantiate the client object
Dim Client As New EasyUAClient
' Read node value and display it
Me.Text1 = Client.ReadValue("opc.tcp://opcua.demo-this.com:51210/UA/SampleServer",
    "nsu=http://test.org/UA/Data/;i=10853")

Try It

It is also easy to communicate with OPC "Classic" servers:

' Create EasyOPC-DA component
Dim Client As New EasyDAClient
' Read item value and display it
Me.Text1 = Client.ReadItemValue("", "OPCLabs.KitServer.2", "Demo.Single")

More...

Example repositories on GitHub: