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Offline Gerard Boor  
#1 Posted : Wednesday, October 31, 2018 11:35:04 AM(UTC)
Gerard Boor

Rank: Newbie

Joined: 10/31/2018(UTC)
Posts: 1

Was thanked: 1 time(s) in 1 post(s)
Hello all,

For an OPC project we are running, I have installed Matrikon OPC Simulator on a cloud VM and configured said VM according to the Matrikon security specs. I set up a second machine in the same way.

On both machines, I can read my custom tags locally with both the OPC Explorer and with the opc.exe command line tool that comes with Python OpenOPC.

I cannot, however, read from machine to machine. I have the firewalls turned off and followed the settings to the letter. I can connect with Matrikon OPC Explorer, but it will not show me any tags or allow me to browse them. No errors are reported when I connect Matrikon OPC Explorer.

When I use the command line opc.exe tool to read a tag on the remote machine, it tells me;

"AddGroup: Access is denied"

Since I have set up the DCOM stuff to the letter, I am really at a loss here.

The production machine can connect just fine to the actual OPC server on the deployment location, but that is really not something we can test with. The settings there are pretty much the same and I can use the command line tool to read all tags from the remote machine. I just cannot get the simulation to work.

Any help would be highly appreciated.
thanks 1 user thanked Gerard Boor for this useful post.
Offline Roger Fortune  
#2 Posted : Thursday, May 30, 2019 7:30:07 PM(UTC)
Roger Fortune

Rank: Advanced Member

Joined: 10/21/2014(UTC)
Posts: 105

Was thanked: 35 time(s) in 32 post(s)
Hi Gerard,

Generally, when Access is Denied is received from a Group call it is the result of a failed callback after the client requests asynchronous subscription. In this case, I would focus on the OPC Client VM's DCOM permissions, specifically the Access Limits. After adjusting these, remember to close / kill your OPC Client application(s) and restart it to pick up the new permissions.

Failing that, download Matrikon OPC UA Tunneller which has free 30 day functionality and see if you can make a connection to the remote OPC Server.
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