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.
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Hi, Mark !
I think that the following list of url's of OPC resources would not be so much.
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 work.so can you help me. tell me some resource or give me some samples which using vc++ or vb.
I think you can get some help in this OPC DA Auto 2.02 Specification.pdf document from http://www.opcfoundation.org .
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 (http://www.opcware.com) 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).
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.
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Looking for OPC servers, look here.
- "www.opcfoundation.org":http://www.opcfoundation.org (you can order the spec and example source)
- "http://www.win-tech.com/html/opc.htm":http://www.win-tech.com/html/opc.htm 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
"www.matrikon.com":http://www.matrikon.com if you download the simulation server and client)
Try downloading the OPC Specification 2.05 from "http://www.opcfoundation.org":http://www.opcfoundation.org web site. It has some very good examples as well as KEPWare has some examples using the OPC specification with their KEPServerEX product.
excellent OPC client tool: OPC ActiveX Controls (Data Access and Alarms and Events), find downloadable demo version on the Softing Web site
I am writting OPC client using Borland C++ Builder, so far I tried as follows:
1. using "www.softing.com":http://www.softing.com 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 "www.wintech.com":http://www.wintech.com , 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 "www.borland.com/codecentral":http://www.borland.com/codecentral 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.
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:
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
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