Does different OPC servers make the difference when try to syncRead

[CalvinChua]

Hi all, I have download a client program which will connects to OPC
server. I have 2 different OPC servers here, one is
OPCDataCtrl.OPCSimServer and another one is Schneider-Aut.OFS.
Category: For Visual Basic
Additional Text: When I choose OPCDataCtrl.OPCSimServer to run with the
program, it works fine, it lets me Read and Write. But when I am connecting
with Schneider-Aut.OFS, it only lets me browse through the symbol table but
not to let me to add the item I chose. Can you tell me why please? Is it
because the I don't have correct setting on the Schneider-Aut.OFS server,
or the symbol table can't be accessed by your program? Your helps and
advices will be appreciated.
Thanks, Wee

[Chris Matthews]

It could be a security issue. That OPC server could require a custom login to add items. What you are using is our DataSocket technology to talk to the OPC item. It doesn't have custom login information in the connection. The server could also be trying to authenticate the source with an OPC Client ID, that DataSocket isn't providing, before allowing a write.

Best Regards,

Chris Matthews
National Instruments

[CalvinChua]

I am connecting OPC server through the IP adress and DCOM. The problem is that I can't AyncRead, SyncRead or Read. Does my OPC server not allow me to Read/Write, but I have another client program in Excel in which I can Read/Write with no problem. One question, do I have to Add the item from OPC into the group I created before I can Read? What is structure and process in order to read and write. The OPC specifications I have is confusing, any explaination and help will be appreciated. Thanks

[aperez]

You mentioned the keyword: DCOM. Getting DCOM servers to runon Win9x is **painful**. I'm not sure if you're on Win9x, but try to run the server on Win NT 4.0 or Win 2k. I prefer the clients also to be Win NT/2k since Win9x was never meant for client/server apps.
If you think DCOM is not setup correctly, you might want to check out the following NI document that explains how to configure DCOM on different OS.

http://zone.ni.com/devzone/conceptd.nsf/2d17d611efb58b22862567a9006ffe76/4466f7754e94da79862569ee00781eb1?OpenDocument

Good luck,

Azucena

[CalvinChua]

I am pretty the DCOM has been setup correctly on our Windows NT machine.