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OPC client programming.
Anyone know of any good OPC resources? I am particularly interested in examples of VB, C++, Delphi and/or Java codee for connecting as a client to an OPC server...
By Mark Hutton on 19 January, 2002 - 2:41 pm

Hi Guy's,

Anyone know of any good OPC resources? I am particularly interested in examples of VB, C++, Delphi and/or Java codee for connecting as a client to an OPC server, but any resources that you know of will be welcome.

Mark Hutton
Software Engineer
YAC # 07092 032237

By Andrew Ronjine on 22 January, 2002 - 2:17 pm

Hi, Mark !
I think that the following list of url's of OPC resources would not be so much.!/






Andrew Ronjine,
Tech. Manager,
Orendurg, Russia.

I am programming opc client using vc++,my opc client need callback dataexchage, If the opc client and server in the same machine,it can work,but if they in different machine,it can not can you help me. tell me some resource or give me some samples which using vc++ or vb.

Hi, Please could u try to use C#.

I think you can get some help in this OPC DA Auto 2.02 Specification.pdf document from .
check your dcom configuration on the target computer.
I also have a vc++ 7 opc client sample, (but I haven't try it) if you want it please mail me.

Am senior in the university of science and technology Beijing (China). Am working on "OPC Application". Please anyone who knows where i can get the very useful information. you can send those informations on my e-mail.

Thanks a lot.

Your client machine DCOM settings need to be configured to allow access to your client application as if it were a server, since for callbacks your client machine is actually the server!

As for resources, I have surveyed the web and written lots of OPC clients with VC++ and VB. At first it seems best to write your own client from scratch, but now I always use OPCWare Client Developer ( as it makes the whole development process much easier, plus they give me great support and can answer questions like yours (I had this same problem, and they gave me the answer).


By Mark Hensley on 22 January, 2002 - 4:35 pm

Hi Mark,

We have some VB examples that come with the demo version of our server. They show you how to use the OPC Automation wrapper in VB. The exmaples provide a lot of comments and demostrate features such as Async Call backs and Tag browsing with all source code included. The exmaples don't use any ActiveX controls or objects other than the OPC Automation wrapper and standard VB controls.

Hope they help.

Mark Hensley
Kepware Inc.
81 Bridge St.
Yarmouth Maine 04096
Looking for OPC servers, look here.

By Gumshoe_2701 on 22 January, 2002 - 4:43 pm

- "": (you can order the spec and example source)
- "": for source examples
- a VB DA client can be done in about under 50 lines of code using the a version of OPC Automation wrapper (you can get a version from
"": if you download the simulation server and client)

OPC ActiveX control resource and some good articles at "": and "":

John Weber

By Hunter Farris on 23 January, 2002 - 10:04 am

Try downloading the OPC Specification 2.05 from "": web site. It has some very good examples as well as KEPWare has some examples using the OPC specification with their KEPServerEX product.

Hunter Farris

By Frank Iwanitz on 24 January, 2002 - 12:24 pm

excellent OPC client tool: OPC ActiveX Controls (Data Access and Alarms and Events), find downloadable demo version on the Softing Web site

By rusman rusyadi on 24 February, 2002 - 12:34 pm

Hi ,

I am writting OPC client using Borland C++ Builder, so far I tried as follows:

1. using "": SOAXC, active X control for client, it works but I could not make its tree to browse, since it crash. sample in
VC++ compile and run OK.

2. using "": , it doesnot work, I can link it but when run it doent connect to server. it works fine when I compile with VC++ 6.

3. using I. munoz's client posting in "": this is really written for BCBuilder. But I need someone help to extend the program to have item browser.

I need to communicate with anyone have the same interest (BCBuilder) with me.

rusman r

Hi Rusman:

I have the same interest as you for c++ builder link to opc server. I download the Munoz example for builder but the compilar report me some errors... my email:

Hi Rusman,
I am a German student and i have to programm a OPC-client with BCB. The example from "Munoz" doesn't work on my PC. A lot of details I can't understand, for example the async read/write and Callback. Do you have some good Info's or articles or books about client programming?
I hope can help me!

Thanks a lot

By Frank Iwanitz on 6 June, 2002 - 7:31 pm


have a look at "":
There you can find a lot of information.



By Tomasz Migdal on 7 June, 2002 - 8:31 pm

Im Polish student and I'm not very good programmer but I need to get some data from OPC Server I got Code of client from borland community (Ionel's) but it doesnt work - some problems in compilation that I dont understand - meybe someone have corected version of this code or just can send me an examle - thanks a lot

Tomasz Migdal