2 clients connecting to opc server

[fps]

I have developed a VB application intended as a Windows Service and have successfully connected the service to the OPC server (everything is great here). I have also developed another VB application intended as a standard EXE and have also successfully connected to the OPC server (everthing is also great here). The problem is trying to run both of these clients at the same time. It appears the the first client loaded connects OK, but the second client will not connect. I have also noticed that I can run multiple instances of the standard EXE client without any connection problems to the OPC server.

I am using:

• Industrial Automation OPC Servers, Version 5.1 (build 4)
• Visual Studio 2008 (VB)
• Measurement Studio for VB.net
• Windows XP Pro SP2

Could someone provide some insight into this problem for me. Your help is greatly appreciated.

Thank you

Chris

[fps]

I believe it might be related to DCOM permissions or Window security etc. Any information would be helpfull.

[Doiron]

Hi Snord,

How exactly are you communicating with the OPC servers?

Are you using a method similar to this?

http://digital.ni.com/public.nsf/allkb/65630616C280E4D486257237006845D1?OpenDocument

Are you using Measurement Sudio Functions in the actual OPC implementation?

Please let me know the answers to these questions so I can assist you further.

[fps]

Hi David,

I am currently using Measurement Studio DataSockets to communicate directly with the OPC Server in both of the clients mentioned above.

I am not sure I understant your second question, but I am using Measurement Studio Controls in one of the clients.

As I mentioned above, both of these clients work as expected when they run independantly. However, when I start the second client (either one) it will not connect to the OPC Server.

Could it be that one client is running under a user account and the other client (Windows Service) is running under the system account???

Chris

[Doiron]

Hi Snord,

What exactly do you mean by "not connecting"? Are you receiving a specific error? Please include a screen shot if so.

Also, are you using a Remote OPC server?

[MadSeb]

I guess we are not using a remote OPC server since the addresses we are using are of the form : "opc://localhost/National Instruments.OPCLookoutDrivers/.."

Our data sockets have the AutoConnect property set to true ...When the service is running, the EXE application gets stuck in the splash screen ( so the data sockets are waiting for a connection )

Sebastian

[MadSeb]

Hello,

I read

http://digital.ni.com/public.nsf/allkb/65630616C280E4D486257237006845D1?OpenDocument

In the "Variable Manager" application : when I click on the "New I/O Server", the listbox for "IO Server Type" is empty.

I don't have the "LabVIEW Datalogging and Supervisory Control (DSC) Run-Time System (RTS). "   ....

Is it really necessary ?

If so, Is it available online for free ?

Regards,

Sebastian

[Doiron]

Hello Sebastian,

It looks like we have two threads on the same (or a very similar) issue. What Chris and I have decided to do is consolidate into his thread which can be found here. Please continue posting there so for support.

Thanks!