Disconnect from OPC DA server

[xujiujing]

Hi everyone,

I am trying to set up a DA to UA Gateway.
Rapidscada and the OPC DA Server are running on different machines.
Communicator and Agent applications were installed on the remote PC.
The ScadaComm6 service was setup to work as the OPCSrv user. Such as this.
The driver is DrvOpcClassic 6.0.1.2.
Rapidscada version is 6.4.1.
It seems Rapidscada could read the variables from the OPC DA server.
However, I got the following error messages after I closing the device property settings (Device Polling):
——————————————————————————–
(Log messages in communication lines)
——————————————————————————–
2025-05-02 21:29:49 Start communication line [1] opcda

2025-05-02 21:29:49 Connect to Matrikon.OPC.Simulation/{f858xxxx-xxxx-xxxx-xxxx-00c0f010xxxx}
Connection to the OPC DA server has been established

2025-05-02 21:29:50 Create subscriptions
Create subscription “” for the device [1] Matrikon (async)
Error creating subscriptions:
0x80040202

2025-05-02 21:31:07 Disconnect from OPC DA server
2025-05-02 21:31:07 Error disconnecting OPC DA server:
0x80040200

2025-05-02 21:31:07 Communication line [1] opcda is stopped
——————————————————————————–

Would you please help me solve this problem?
Thanks a lot in advance!

[Mikhail]

Hi,

> Rapidscada and the OPC DA Server are running on different machines.
When OPC DA server and client are installed on different machines, it requires setup of DCOM security. You should search for DCOM manuals. Sometimes a user manages to run it.
I recommend installing Communicator on the same machine where the OPC server is already installed.

[xujiujing]

Hi Mikhail,

Thanks a lot for your reply. My DCOM configuration was reset by accident. I’ve now managed to get everything working again.

Many thanks for your support and guidance.

Best regards
Jiujing Xu

[xujiujing]

Hi Mikhail,

I am performing the same task with another OPC DA server running on a different machine.

DCOM configuration has already been completed.

Using the “MatrikonOPC Explorer” OPC DA client, I am able to successfully connect to the remote OPC DA server. However, when attempting to access the server using Rapid SCADA, I encounter an error: “CoCreateInstanceEx denies access.”

Both machines have installed the following components:
OPC Core Components Redistributable (x64) 3.00.108
OPC Core Components Redistributable (x86) 3.00.108

Could you please advise on how to resolve this issue?
Thank you very much for your help in advance. Wishing you a great day!

Best regards,
Jiujing Xu

[xujiujing]

Hi Mikhail,

Sorry to bother you again. It seems that my OpcEnum configuration has been changed once more. The connection is working fine now.

Best regards,
Jiujing Xu

[Mikhail]

Hi,
Thanks a lot for the update.

[RhysGoodwin]

Hi,

For others who come across this, some hopefully usful tips for using Rapid SCADA to connect to a remote OPC-DA server in a workgroup (non-domain joined) environment.
– Create local accounts with matching username and passwords on both servers
– On the OPC-DA server side:
– Ensure the user has sufficient decom permissions
– Ensure SID filtering is disabled:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
LocalAccountTokenFilterPolicy=1

– On the Rapid SCADA server:
– Make the local user an admin (at least for testing, it may be possible to lock it down later)
– Make sure to run the Rapid SCADA admin tool as this local user
– Make sure to run the Rapid SCADA ScadaComm6 system service as this user
– Set app-specific DCOM authentication for ScadaComm6 with the following reg import:This should fix `Error creating subscriptions:
0x80040202`

Windows Registry Editor Version 5.00
; Make your own GUI with PowerShell: [guid]::NewGuid()
; Tie the EXE to an AppID (so it appears under DCOM Config)
[HKEY_CLASSES_ROOT\AppID\ScadaCommWkr.exe]
"AppID"="{9a9a27c6-3317-405a-a364-ce4eb1878a95}"

; Define the AppID node with a friendly name (what you’ll see in DCOMCNFG)
[HKEY_CLASSES_ROOT\AppID\{9a9a27c6-3317-405a-a364-ce4eb1878a95}]
@="Rapid SCADA - ScadaComm Worker (OPC-DA Client)"
; Optional: per-app authentication level. 0=Default, 1=None, 2=Connect, 3=Call, 4=Pkt, 5=PktIntegrity, 6=PktPrivacy.
"AuthenticationLevel"=dword:00000001

Cheers,
Rhys

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