Unable to connect to remote OPC server using DSC Module and I/O server.

[Terje]

For a long time I have tried to connect my LabView program to a remote OPC server using LabView with the DSC Module. I have also posted a similar question on this forum last year:http://forums.ni.com/ni/board/message?board.id=170&thread.id=356616

After upgrading to LabView 2009 I found a program called NI OPC Quick Client. With this program I was able to connect and view data on the remote server. What it so annoying is that although I’m able to connect to the OPC server using NI OPC Quick Client or using DataSocket, I’m still not able to connect to the server using the I/O server with the DSC Module. What can that be? Is the I/O Server more picky regarding OPC servers than the NI OPC Quick Client and DataSockets?

Terje

[Norbert_B]

Terje,

does a local access using a DSC  IO-server work? If yes, this is what i recommend you to use.

1. Create a local IO server in your hosting system (so the machine running the OPC server). You will need a DSC license on this machine for this.

2. Create a LV project on your client machine and create a shared variable. Bind this variable using Aliasing >> Bind to PSP URL to one of the variables of your IO server. You don't need a DSC license for this.

The advantage of this is that you do not need to configure any DCOM settings. You still need only a single DSC license, it will simply move from client to server. And, finally, experience shows that this approach is way more stable than remote OPC using DCOM......

hope this helps,

Norbert 

PS: PSP is "publish subscriber protocol" and is the protocol shared variable are based on. In order to have this working, you will need the shared variable engine (SVE) running and accessable in the network (firewall?!)

[Terje]

Hi Nobert and thanks for your reply.

Unfortunately, the remote computer is a commercial robot controller running windows XP embedded. I would rather not install anything of my own on that computer and I don’t even know if that is possible. What troubles me is that I have tried many OPC Clients (One shipped with the robot controller, Matrikon OPC and NI OPC Quick Client) and they have no problem at all reading the variables from the OPC server, but I have no luck with the I/O Server. Reading on related problems on this forum, I have realized that the problem probably is related to security settings for DCOM. I used a lot of time trying to resolve the problem the first time that I encountered it last year, but had to give up. When I now saw that NI’s own OPC client managed to connect to the server with no problem, I thought perhaps the implementation of the NI OPC Quick Client was similar to the implementation of the I/O Server. But as I'm still not able to connect with the I/O server, either I am doing something wrong or the I/O Server is more sensitive to security settings than other OPC clients.

Terje

[Norbert_B]

Terje,

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Terje wrote:
[...]When I now saw that NI’s own OPC client managed to connect to the server with no problem,[...]

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the NI OPC Quick Client is the OEM version of a Kerpware OPC Client. So this is not directly comparable to the NI OPC client.

Please note that OPC is not an easy stuff since the OPC definition is "wide spread". It is remarkable, that a company lives from supplying OPC interconnection tools (Matrikon would be the company 🙂 ).

So maybe you can use the Matrikon OPC to get the connection to your server from your client side. Then connect from LV to the Matrikon server. This setup is as far as i know quite good except from the need of an additional tool (Matrikon "tunneler")....

hope this helps,

Norbert 

[Terje]

That is a solution that I have not considered. I will check it out.

Thanks you Norbert