If you have an OPC Client for Delphi, it should be fairly easy. If you are trying to develop an OPC Client for Delphi, then it will probably be quite a bit more difficult. I would recommend taking a look at National Instruments Application Note 139: Developing an OPC Client Application Using Visual Basic. The App Note centers around using DataSockets as a Visual Basic OPC Client and uses the FieldPoint OPC Server for it's examples. Whereas you will probably not be using DataSockets as your OPC Client, the App Note provides some good information on the FieldPoint OPC Server naming structures. It can be found at:
http://zone.ni.com/devzone/conceptd.nsf/webmain/87D5C15CAFB2654A86256874005C280C/$File/AN139.pdf
Regards,
Aaron
LabVIEW Champion, CLA, CPI