OPC DA client communication won’t work due to authentication failure.

Question:

What could have caused a communication failure via Elipse E3‘s OPC DA client? I suspect the server isn’t accepting the client’s authentication. In this example, I’m using GE’s B&R.DviOPC.2 server.

Solution:

Before performing the configuration procedures described in this article, we suggest that you check if both the firewall and DCOM were properly released, not only with the OPC DA client but also with the server. Therefore, we recommend reading the following articles:

• DCOM and Firewall Settings in Windows 7 for Elipse applications..
• DCOM and Firewall Settings in Windows XP/2003/Vista/2008 for Elipse applications..

If even after this configuration the communication with the OPC DA client hasn’t been established, it’s possible the connection has an authentication problem. In order to increase the OPC DA client’s authentication level, follow these procedures:

1. Firstly, open the  DCOM objects configuration window (type dcomcnfg at Windows search bar).
2. Once you’re at Computer -> Meu Computer -> DCOM Settings, locate the E3OpcClient object.
3. Then, access this object’s properties window, and change the authentication level no  None.
4. Finally, run the OPC DA client communication again at E3 Studio.

Related articles:

• DCOM and Firewall Settings in Windows 7 for Elipse applications.
• DCOM and Firewall Settings in Windows XP/2003/Vista/2008 for Elipse applications.
• KB-30877: OPC communication only works via Studio.
• KB-39425: OPC communication not working, even after DCOM has been set up.