800xA 5.1: error when adding a remote OPC node ("could not access the specified computer!") - firewall isse?
See the attached screenshot. I get the following error when trying to add a remote OPC server:
"Could not access the specified computer! Error: The network path was not found. (0x80070035)".
There is a firewall between the OPC node and the connectivity server, and I think this is the reason for the error.
I need to know exactly what services/ports need to be allowed in the firewall for this to work. I know port TCP 135 for DCOM/OPC must be open, but what else?
(I have already tested the OPC connection between the connectivity server and the remote OPC server node using a third-party OPC client and it does work.)
This is the downside with DCOM.
Remember that the outgoing connection from System 800xA will be made from a process called AdvDsOPCConnector.exe running as a background service. A background service has less features enabled (eg no GUI possible) than a process running in the foreground, eg an OPC test client. OPC servers having a splash screen need to disable it, or they will hang when launched from the 800xA DA Connector.
For asynchronous DCOM, please note that OPC server must be permitted to post callbacks to the client (=AdvDsOPCConnector.exe).
See also attachments to my answer on this thread (http://www402.abbext.com/800xa-opc-cl...). This is opposite direction, but the DCOM restrictions apply here as well.
Ultimately, an OPC Tunneler might be the easiest way out.