KEPServerEX OPC UA Client Driver Unable to Connect to CIMON OPC UA Server

[uvcssb]

1. Current Situation

CIMON OPC UA Server Information:

• IP: [CIMON OPC UA Server IP]
• Port: [CIMON OPC UA Server Port]
• Network: Same local network (Ping test and TCP connection successfully confirmed).

KEPServerEX Status:

• The OPC UA Client Driver in KEPServerEX cannot detect the CIMON OPC UA Server during server discovery.
• Even when the Endpoint URL is manually entered, the connection fails.

Other Client Status:

• UaExpert:
  • Successfully connects to opc.tcp://[CIMON OPC UA Server IP]:[CIMON OPC UA Server Port] (with Security Policy: None, Message Security Mode: None).
  • Node browsing and data reading from the CIMON OPC UA server work perfectly.
• Node.js (node-opcua library):
  • Successfully connects to the same Endpoint URL and reads data successfully (with Security Policy: None, Message Security Mode: None).

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2. Troubleshooting Attempts

Network Connection Check:

• From the machine running KEPServerEX ([KEPServerEX Machine IP]):
  • Ping to [CIMON OPC UA Server IP] → Successful response.
  • Test-NetConnection [CIMON OPC UA Server IP] -Port [CIMON OPC UA Server Port] → TCP response successful.
• No network connection issues detected between KEPServerEX and CIMON OPC UA Server.

Firewall Configuration:

• Allowed TCP Port [CIMON OPC UA Server Port] on the machine running KEPServerEX ([KEPServerEX Machine IP]).
• Configured both inbound and outbound rules.

Security and Authentication:

• Configured KEPServerEX with Security Policy: None and Message Security Mode: None to match the CIMON OPC UA Server.

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3. Main Issue

The issue does not appear to be related to network connectivity or security/authentication configurations.

While other clients (UaExpert, Node.js-based clients) successfully connect to the CIMON OPC UA Server, only KEPServerEX fails to discover or connect to the server.

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4. Environment Details

• KEPServerEX Version: v6.17.240.0
• Machine Running KEPServerEX:
  • IP: [KEPServerEX Machine IP]
• CIMON OPC UA Server:
  • IP: [CIMON OPC UA Server IP]
  • Port: [CIMON OPC UA Server Port]
  • Security Settings: Security Policy None, Message Security Mode None
• Network Environment: Same local network, TCP Port [CIMON OPC UA Server Port] allowed through the firewall.

[rajskumar · Accepted solution]

Hello, Thank you for the detailed description.

Are you encountering any errors while browsing the CIMON OPC UA Server (in manual connection)? Please verify the client-side configuration using the article below.

https://www.ptc.com/en/support/article/CS298913

If you are prompted to log in to view the complete article, you can use your MyKepware login credentials.

Additionally, I suggest capturing Wireshark packets to identify the issue.

[uvcssb]

Current Situation

1. CIMON OPC UA Server Details

   • IP: [CIMON_IP]
   • Port: 4840
   • Security Policy: None
   • Message Security Mode: None

2. UaExpert Connection

   • Successfully connects to the CIMON OPC UA Server, allowing node browsing and data reading.

3. Node.js Connection

   • Successfully connects to the CIMON OPC UA Server, enabling data read/write operations.

4. KEPServerEX Connection

   • Using the OPC UA Client Driver, attempting to connect to the CIMON OPC UA Server results in a BadTcpMessageTooLarge error.
   • Wireshark packet analysis shows that after sending a GetEndpointsRequest, the CIMON OPC UA Server returns this error.

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Wireshark Request Packet Comparison

1. UaExpert Request Packet:

   • Message Size: 98 bytes
   • Details:
     • EndpointUrl: opc.tcp://[CIMON_IP]:4840
     • LocaleIds: None (ArraySize: 0)
     • ProfileUris: None (ArraySize: 0)

2. KEPServerEX Request Packet:

   • Message Size: 167 bytes
   • Details:
     • EndpointUrl: opc.tcp://[CIMON_IP]:4840
     • LocaleIds: None (ArraySize: 0)
     • ProfileUris: 1 URI included (http://opcfoundation.org/UA-Profile/Transport/uatcp-uasc-uabinary)

3. TCP Segments Comparison:

   • UaExpert Request: Sent in a single TCP segment.
   • KEPServerEX Request:
     • Reassembled TCP Segments:
       • Frame #101: 12 bytes
       • Frame #102: 4 bytes
       • Frame #103: 151 bytes
     • Total Length: 167 bytes
   • It seems the CIMON OPC UA Server might have trouble handling segmented TCP packets from KEPServerEX.

4. Comparison Results:

   • KEPServerEX’s request is slightly larger due to the inclusion of ProfileUris.
   • However, 167 bytes is not typically considered a "large message" in OPC UA communications.
   • UaExpert successfully handles requests larger than 167 bytes without issues.

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Steps Taken to Resolve

1. Network Connection

   • Ping and TCP connection tests confirm accessibility (Port 4840).

2. KEPServerEX Configuration

   • Configured with Security Policy: None, Message Security Mode: None.

3. Wireshark Analysis

   • Compared request message size and TCP segments between UaExpert and KEPServerEX.
   • KEPServerEX’s request is sent in multiple TCP segments, which might not be properly handled by the CIMON OPC UA Server.

[uvcssb]

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Current Situation

CIMON OPC UA Server Details

• IP: [CIMON_IP]
• Port: 4840
• Security Policy: None
• Message Security Mode: None

UaExpert Connection

• Successfully connects to the CIMON OPC UA Server, allowing node browsing and data reading.

Node.js Connection

• Successfully connects to the CIMON OPC UA Server, enabling data read/write operations.

KEPServerEX Connection

• Using the OPC UA Client Driver, attempting to connect to the CIMON OPC UA Server results in a BadTcpMessageTooLarge error.
• Wireshark packet analysis shows that after sending a GetEndpointsRequest, the CIMON OPC UA Server returns this error.

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Wireshark Request Packet Comparison

UaExpert Request Packet:

• Message Size: 98 bytes
• Details:
  • EndpointUrl: opc.tcp://[CIMON_IP]:4840
  • LocaleIds: None (ArraySize: 0)
  • ProfileUris: None (ArraySize: 0)

KEPServerEX Request Packet:

• Message Size: 167 bytes
• Details:
  • EndpointUrl: opc.tcp://[CIMON_IP]:4840
  • LocaleIds: None (ArraySize: 0)
  • ProfileUris: 1 URI included (http://opcfoundation.org/UA-Profile/Transport/uatcp-uasc-uabinary)

TCP Segments Comparison:

• UaExpert Request: Sent in a single TCP segment.
• KEPServerEX Request:
  • Reassembled TCP Segments:
    • Frame #101: 12 bytes
    • Frame #102: 4 bytes
    • Frame #103: 151 bytes
  • Total Length: 167 bytes
• It seems the CIMON OPC UA Server might have trouble handling segmented TCP packets from KEPServerEX.

---

Comparison Results

• KEPServerEX’s request is slightly larger due to the inclusion of ProfileUris.
• However, 167 bytes is not typically considered a "large message" in OPC UA communications.
• UaExpert successfully handles requests larger than 167 bytes without issues.

---

Steps Taken to Resolve

Network Connection

• Ping and TCP connection tests confirm accessibility (Port 4840).

KEPServerEX Configuration

• Configured with Security Policy: None, Message Security Mode: None.

Wireshark Analysis

• Compared request message size and TCP segments between UaExpert and KEPServerEX.
• KEPServerEX’s request is sent in multiple TCP segments, which might not be properly handled by the CIMON OPC UA Server.

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