OPC server access remotely using OPCDA.NET tools

Question

I am developing OPC Client in windows C#. I have developed the code and reading OPC Items on Sampling as well as event based (OnDataChange). When I am working with local machine then my code works fine with both Sampling as well as OnDataChange, but when I am trying to read data from Remote OPC Server then Sampling works fine but I am not able fetch data on event based process. I am able to connect to the OPC Server but when i am adding subscription to it then i am getting error.

HRESULT : 0x80040202.

       group1.DataChanged += new DataChangeEventHandler(this.DataChangeHandler);
               group1.AdviseIOPCDataCallback();//exception HRESULT : 0x80040202.

OPC server connected & then register the group also but i got the exception when reading data.

Answer 1

The problem you are actually having is with the callback. In other words, it isn't the advise call that is failing you, it is the callback from the OPC server (which advise triggers). This error is usually caused by user authentication problems (i.e. the user accounts do not match on both computers). Check out the OPC server's user account on the remote computer. If it doesn't exist on your local computer, you found the problem!

There is an automated application to help you figure out your problem. I recommend you download OPC Expert (Google it). It is a free application, does not require installation, and does not change Windows Registry. It has saved me many times. Also, the vendor (OPCTI) is extremely helpful, so check them out.

Answer 2

The issue usually is that when you use Advise(), the server will make a DCOM connection back to the client (standard DCOM connection points). The client needs to be set up properly to allow this to happen (i.e. the right security settings to allow the server to execute code on the client).

You should read this page: http://www.softwaretoolbox.com/xpsp2/, it covers a lot of recommendations on how to set up DCOM properly for OPC usage. There are a lot of security concerns here. The Software Toolbox site has a lot of great information (and videos too). If you are still having trouble getting it to work, I recommend investing in an OPC tunneling product that will allow you to do remote OPC without having to jump through all the DCOM loops.

You don't have to be using OPCDA.NET to have the same issue. You can use any OPC client and get it working first with your remote server, then focus on figuring out how to get it all hooked up in OPCDA.NET. I recommend OPC Quick Client (comes with Software Toolbox TOP Server demo).

Answer 3

That problem is because when you connect to the server, you might use the first connect function, which is server.connect();

Instead, try:

server.connect(new Opc.ConnectData(new System.Net.NetworkCredential()));

This works for me. Hope it helps:)