Configure Windows Firewall to Allow OPC Server Communication

Updated Nov 23, 2020



  • OPC Servers
  • LabVIEW

Operating System

  • Windows

I'm trying to connect to an OPC server programmed in LabVIEW with another LabVIEW program. I can connect locally to the server, but I'm not able to through our firewall.
  • How do I configure the firewall? 
  • What is the port used in LabVIEW for OPC servers? 


To allow for communication with the OPC server, you will need to add the proper protocol and port exceptions to the Windows Firewall: 

Protocol Exceptions: 
  • All OPC clients and servers
  • Microsoft Management Console
  • OPC utility OPCEnum.exe (located in Windows\System32 directory)

Port Exception:
Name: DCOM
Port number: 135
Type: TCP 
The steps to add the protocol and port exceptions to Windows Firewall will vary depending on your computer OS. See the instructions for: