DAQ OPC on Windows XP

[John_Howard]

Since some of you use OPC, maybe someone will have an idea what I am doing wrong here.

I have two Windows XP Pro SP1 computers. Both have the following common software installed:

MAX 3.0.2.3005
NI-DAQ 7.1.0f1
DAQmx 7.1.0f1
Server Explorer 2.4.1 (National Instruments)

I have some virtual channels set up for NI-DAQ, just to make sure DAQ OPC has something to look at.

In Server Explorer, when I try to browse the OPC Servers on the remote computer, I consistently get the Windows error message "Unable to connect to \\! Make sure that this computer is on the network, has remote administration enabled, and that both computers are running the remote registry service."

If I try to view the resistry keys on the remote
computer using 'regedt32', I can not view anything below HKEY_LOCAL_MACHINE\SYSTEM, even though I have modified security for the following keys to make sure DCOM should work.
"HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurePipeServers ..."
I gave "Everyone" full access to these keys just to be sure security wouldn't be a problem.

Does anyone know if there is anything peculiar about Windows XP that might make DAQ OPC setup difficult (or maybe just different). I've done all the DCOM setup stuff that National Instruments recommends. I am using the Adminstrator account on both computers (same password for both). I am trying to use the simplest possible settings, and it just doesn't seem to want to work!

A National Intruments engineer has been trying to help me as well, and I seem to have him stumped.

Thanks for any ideas!

John Howard

[BrandonS]

I have been able to reproduce the error that you are seeing. I set up dcom for DAQ OPC and then ran everything without any problems. I then thought what might be causing the error that you were receiving. I had an administrative account on both computers with the same user name. If I removed the user from the server computer, I got the same error you are reporting. After I added my user back in as an administrator everything worked correctly. This might be something to explore.

[Robert_Jackson]

Great job supporting our community, for more information this Knowledgebase describes the process for configuring Remote OPC on Windows NT/2000/XP.
http://zone.ni.com/devzone/conceptd.nsf/webmain/3EA0C311BD5AD012862569EE007BB22F?opendocument

NI recommends using the same user account on both machines for troubleshooting.

Regards,
Robert Jackson
Application Engineer

[John_Howard]

Thanks for the responses. However, after two more weeks of frusteration I have discovered that there is more to this than meets the eye.

Part of my confusion has been that I AM using the same account on all the computers (the "Administrator" account). Here is one more setting I had to change to get everything working properly.

Apparently, the default setup for XP forces remote users to authenticate as Guest. (there must be a logical reason Microsoft changed this - but it is beyond me) This means that DCOM clients (OPC) can not connect to a server on an XP machine unless the Guest account is activated AND has sufficient rights to launch the server. Here is how you change this setting:

Go to "Administrative Tools" > "Local Security
Policy" > "Local Policies" > "Security Options" > "Network access: Sharing and security model for local accounts"

You need to change this setting to "Classic - users authenticate as themselves".

After doing this you won't need to activate the Guest account.

Once I did this everything FINALLY started working. Perhaps this is only a problem when using the Administrator account? I don't know but I just glad to finally get past this!

John Howard

[John_Howard]

Thanks Brandon! You certainly were onto something here. See my comment below for more details.

John Howard