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D
DLAN_REDB4-Participant
4-Participant
June 29, 2026
Question

OPC DA Client Connection to OPC Server

  • June 29, 2026
  • 7 replies
  • 129 views

I am currently testing Kepware Server 7 to connect to an OPC Server via OPC DA.The OPC Server, in production, is currently has working OPC DA Client. I have configured the DCOM configuration for the Kepware Server.
Set the Launch and Access Permission default and limits with the user that is also in the OPC Server as well as Access Permission. I can browse the tags but when OPC Quick Client (OQC) is connected to the Kepware, data is Bad and not updating. Here are what I observe during the testing:

  • Data is updating:            Kepware Runtime “Use DCOM configuration” = disabled
  • Data is not updating:      Kepware Runtime “Use DCOM configuration” = enabled
  • Data is updating:            “My Computer” authentication level = None and “Use DCOM remote security” is enabled (connected directly to OPC Server)
  • Data is not updating:      “My Computer” authentication level = Default/Connect and “Use DCOM remote security” is enabled. (connected directly to OPC Server)

However, I tried to set the authentication levels to None with OpcEnum and Kepware Server in dcomcnfg just to replicate the “My Computer” None authentication level, Kepware still don’t give updates with the browsed tags.

I have tried the interactive user and system service for the runtime and still cannot get asynchronous callbacks updates. Synchronous Poll is working but is not the ideal solution. The server is in production so we are strictly not allowed to just change the DCOM configuration of it but as mentioned, there is already existing OPC DA client of it.

7 replies

Sankalp Yadav
Sankalp Yadav5-Regular Member
5-Regular Member
July 1, 2026

Check the below requirement as well:

  • Firewall is disabled or allow port 135.
  • If using remote system to connect with Kepware then Login credential must be same.
Sankalp
D
DLAN_REDB4-ParticipantAuthor
4-Participant
July 7, 2026

I have both the server’s firewall disabled.
I have created a login user account to be the same.
The problem is the Asynchronous callback since I tested using Poll and Synchronous and it is working. However, when it is said to the ideal Exception (asynchronous), it is not working. I have set the Kepware client to Connect (same as the server authentication level). I am still lost as we already restarted the OPC server with the updating DCOM permissions for Limits and Defaults in both Launch and Activation Permission and Access Permission.

Sankalp Yadav
Sankalp Yadav5-Regular Member
5-Regular Member
July 10, 2026

May I know which OPC server you are using e.g., ABB, Yokogawa etc. It will help understand the setup.

Sankalp
D
DLAN_REDB4-ParticipantAuthor
4-Participant
July 14, 2026

I am connecting to an Ovation OPC Server.

M
MRohillaCommunity Manager
Support
July 21, 2026

Greetings ​@DLAN_REDB,

There might be possible that the DCOM configuration has missed some permission which are restricting the Kepware to do handshake with the OPC DA server. Also confirm if the Matrikon application is installed on same machine where kepware instance available?

Please go through our DCOM Configuration guide at the below link:

Remote OPC DA (DCOM) Configuration Guide


My cliff notes below correspond to the 7 sections of the guide and which side(s) they apply to:

Section 2: (Workgroup Only) (Both sides) [add matching UN and PW]
Section 3: (Server side) [Runtime process and DCOM enabled]
Section 4: (Server side)* [config all users and groups] => (Add Administrators, Anonymous, System, Everyone and Network with complete permission )

 Section 4.2: (Interactive Mode Only) (Server side)[Configuring the Application Identity]
Section 5: (Both sides) [Firewall]
Section 6: (Both sides) [Enable Network disco]
Section 7: (Workgroup Only) (Both sides) [Local Sec Pol]

*Section 4: IF you can't get connected with just adding Administrators, Anonymous & System to the control Lists, try adding Add "Everyone" and "Network".

Not in guide: UAC: Set User Account Control to the lowest level on both machines.

*Section 5: If you are unable to allow the applications through the firewall - you need to set the Dynamic Port Range, for the OS KEPServerEX is running on, through the firewall.

Dynamic RPC Port Ranges:
Windows XP: 1025-5000
Windows Vista: 49152-65535
Windows 7: 49152-65535
Windows 8: 49152-65535
Windows 10: 49152-65535
Windows Server 2000: 1025-5000
Windows Server 2003: 1025-5000
Windows Server 2008: 49152-65535
Windows Server 2012: 49152-65535
Windows Server 2016: 49152-65535

There might be possible that the DCOM configuration has missed some permission which are restricting the Kepware to do handshake with the OPC DA server. Also confirm if the Matrikon application is installed on same machine where kepware instance available?

Please go through our DCOM Configuration guide at the below link:

Remote OPC DA (DCOM) Configuration Guide


My cliff notes below correspond to the 7 sections of the guide and which side(s) they apply to:

Section 2: (Workgroup Only) (Both sides) [add matching UN and PW]
Section 3: (Server side) [Runtime process and DCOM enabled]
Section 4: (Server side)* [config all users and groups] => (Add Administrators, Anonymous, System, Everyone and Network with complete permission )

 Section 4.2: (Interactive Mode Only) (Server side)[Configuring the Application Identity]
Section 5: (Both sides) [Firewall]
Section 6: (Both sides) [Enable Network disco]
Section 7: (Workgroup Only) (Both sides) [Local Sec Pol]

*Section 4: IF you can't get connected with just adding Administrators, Anonymous & System to the control Lists, try adding Add "Everyone" and "Network".

Not in guide: UAC: Set User Account Control to the lowest level on both machines.

*Section 5: If you are unable to allow the applications through the firewall - you need to set the Dynamic Port Range, for the OS KEPServerEX is running on, through the firewall.

Dynamic RPC Port Ranges:
Windows XP: 1025-5000
Windows Vista: 49152-65535
Windows 7: 49152-65535
Windows 8: 49152-65535
Windows 10: 49152-65535
Windows Server 2000: 1025-5000
Windows Server 2003: 1025-5000
Windows Server 2008: 49152-65535
Windows Server 2012: 49152-65535
Windows Server 2016: 49152-65535

Regards,

Mohit

D
DLAN_REDB4-ParticipantAuthor
4-Participant
July 22, 2026

Hi Mohit thank you for your response,

Yes the MatrikonOPC Explorer is installed on the same machine where the Kepware instance is also found.
I have done the Remote OPC DA (DCOM) Configuration Guide when configuring our Kepware Server instance as well as on the Ovation side.
Section 3: The process mode on the Ovation server and Kepware Server is both running as Service. The Ovation is running as LocalSystem while on the Kepware Runtime, we tried LocalSystem and the replicated local user to run the runtime service.

Section 4: We have yet to check but Everyone and ANONYMOUS LOGON on both the Limits of Access and Launch and Activation Permissions were added on both the client and server side.
Section 5: Both Windows Firewalls were turned off and no firewall exists between the dev machine and the OPC server.
Section 6: The server can be discovered on Windows Explorer when IP address is inserted and a prompt for user account is displayed.

Section 7: Both are set to Classic and on the Client side, the setting is enabled when applying the anonymous logon to everyone.

Btw, the server has an existing client and we replicated its settings to the machine where Kepware Server is running.

M
MRohillaCommunity Manager
Support
August 6, 2026

Greetings ​@DLAN_REDB ,

If the issue still persists, then we need a ticket from you end so that we can connect remotely and take a look at the configuration. You can open a ticket at My.Kepware.com. Once you submit a ticket i request you share the ticket number in private message with us.
Let us know if you need assistance in raising a ticket 

Regards,

Mohit

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