Connectivity with the OPC UA server

The connectivity with the OPC UA Server can fail for one or more of the following reasons:

• The OPC UA Server is not running, and is is not discoverable.

• The configuration on the OPC UA faceplate does not match that on the OPC UA Server.

• The firewall settings on a specified port blocks the OPC UA Server connectivity.

Diagnosing the Firewall Constraints

You can diagnose the firewall constraints leading to the OPC UA server connectivity failure by one of the following methods.

Method 1: Using Telnet to diagnose the connection

1. Enable the Telnet Client Windows feature in Windows Features configuration panel.

2. Open the Command Prompt window, and type Telnet <IP Address> <port>

   Example: Telnet 10.228.106.139 48010

3. If the connection is successful, the Command Prompt window goes blank. Else, the command will timeout.

Method 2: Use PsPing utility from Windows SysInternals

4. Open the Command Prompt window, and type Psping -t <IP Address>:<Port Number>

   Example: psping –t 10.228.106.139 48010

5. If the target node/port is reachable and not blocked by the firewall, the command will return the duration in milliseconds.

Resolving the OPC UA Server connectivity failure

Ensure that the firewall configuration in the target node (where OPC UA server is running) allows this connection. You can manage the firewall settings using one of the following solutions.

Solution 1: Register the program through an Inbound Rule (Program)

6. Open the Windows Defender Firewall control panel item, and select Advanced Settings.

7. Select Inbound Rules, and select New Rule.

8. In the New Inbound Rule Wizard, select Program, and select Next.

9. Select This program path:, and use the Browse button to select the program (.exe file), and select Next.

10. Select Allow the connection and select Next.

11. For When does this rule apply?, select Domain, and select Next.

12. Give a name and description for the setting, and select Finish.

Solution 2: Register the program through an Inbound Rule (Port)

13. Open the Windows Defender Firewall control panel item, and select Advanced Settings.

14. Select Inbound Rules, and select New Rule.

15. In the New Inbound Rule Wizard, select Port, and select Next.

16. Select TCP, and enter the port number in the Specific local ports field. Select Next.

17. Select Allow the connection and select Next.

18. For When does this rule apply?, select Domain, and select Next.

19. Give a name and description for the setting, and select Finish.

Solution 3: Modify the Incoming Connection rule

20. Open the Windows Defender Firewall control panel item, and select Turn Windows Defender Firewall on or off.

21. Under Domain network settings, clear the Block all incoming connections… check box.