Here you have various, very old and untested, solutions and examples for Delphi. Last time I was dealing with this examples around 2008, so yeah -- they're quite old and pretty useless.

Key Features Discover external programming libraries that will speed up your programming and code Learn to integrate external libraries into Delphi programs Build fast Delphi applications using ...

This directory contains examples for OPC client and subscriber development in Object Pascal (Delphi IDE). The examples cover OPC Data Access (OPC DA), OPC Alarms&Events (OPC A&E), OPC XML, and OPC ...