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4-Participant
June 29, 2026
Question

OPC DA Client Connection to OPC Server

  • June 29, 2026
  • 2 replies
  • 67 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.

2 replies

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

I am connecting to an Ovation OPC Server.