Troubleshoot WinCC OPC UA Discovery When the Server Is Missing

For classic WinCC V7.4, Siemens' V7.4 SP1 example identifies the WinCC OPC UA server as part of the Connectivity Pack option package, requiring that package to be installed and a valid license present. The OPC UA endpoint's documented default port is 4862; port 4840 is associated with OPC UA Local Discovery, not the WinCC server endpoint. In the reported PCS 7 V9.0 SP2 system, no OpcUaServerWinCC service was present, so verify the server component installation and use the actual WinCC endpoint before troubleshooting client browsing.

Applies To

The original question began with WinCC V7.4 but later reports PCS 7 V9.0 SP2, an active Connectivity Pack license, no OpcUaServerWinCC Windows service and tests against opc.tcp://localhost:4840. Siemens' V7.4 OPC UA example applies specifically to WinCC V7.4 SP1 Update 2. The source does not establish the exact WinCC version bundled in the PCS 7 V9.0 SP2 installation or whether the OPC UA server component was selected during setup.

Separate the Discovery Service from the WinCC Endpoint

Siemens' WinCC V7.4 example gives port 4862 as the default WinCC UA server port and says it can be adjusted in the relevant XML configuration. Siemens port documentation identifies 4840 as OPC UA Local Discovery Server. Therefore opc.tcp://localhost:4840 should not be assumed to be the WinCC runtime server address. Use the WinCC server's configured endpoint, normally opc.tcp://<WinCC-host>:4862 when the default applies. A discovery service can help enumerate endpoints, but a discovery URL and a server endpoint are different addresses.

Check the Installed Server Component

Confirm the exact WinCC release installed on the OS station and whether it is classic WinCC V7 or WinCC Professional. Do not apply classic V7 setup or licensing rules to WinCC Professional.
In the installed-product/component list for the matching WinCC/PCS 7 installation, check whether the WinCC OPC UA Server component and Connectivity Pack option package were installed. Siemens' V7.4 SP1 example says the server is integrated in V7.4 and available when the Connectivity Pack option package is installed and a valid license is present; it does not support the blanket claim that it is always enabled without configuration.
If the component is absent, use the original, version-matched installation media and its maintenance/modify workflow to add the documented component. Check PCS 7 compatibility and change-control requirements before modifying a validated OS station. The exact component labels for PCS 7 V9.0 SP2 were not available in the opened documentation.
Start the OS project Runtime and check whether the WinCC OPC UA service is installed and running. In the reported case the service was absent; this is consistent with an installation/component issue to investigate, but is not proof of the cause.

Verify Licensing and Runtime Configuration

For classic WinCC V7, Siemens' OPC checklist states a Connectivity Pack license is required to operate WinCC with an OPC UA server, and the license must be stored on each concerned server. The ticket reports a license status that was not in use, but that observation alone does not establish whether the OPC UA server option was installed, activated or correctly licensed. Verify license visibility on the actual OS server and check the WinCC project's server/OPC UA configuration for the exact release. A license does not install a missing software component.

Test the Correct Endpoint Locally

Start the WinCC OS Runtime on the server and confirm the OPC UA server service is present and running.
In UA Expert or another OPC UA client, connect to the configured WinCC endpoint. For the documented WinCC V7.4 default, test opc.tcp://localhost:4862 locally; use the configured host and port from the server's configuration if changed.
Request or browse the server endpoints. Siemens' V7.4 example uses the GetEndpoints operation and documents that the initial unencrypted endpoint may be used before certificate exchange, where the security policy permits it. If the system requires secure communication, configure and trust certificates instead of weakening site security.
If local connection works but remote connection does not, investigate host resolution, firewall rules, certificates and security policy for the installed version. Do not troubleshoot OPC DA/DCOM settings as if they governed OPC UA; the two OPC generations use different communication/security mechanisms.

Interpret the Missing-Service Symptom

If OpcUaServerWinCC does not appear in Windows Services, first determine whether the version-matched OPC UA server component was installed. Then verify the product version, option package, license and OS runtime state. Searching only for OPC UA Local Discovery Server or OPCEnum does not confirm that the WinCC server is installed. Conversely, if the server service exists but is paused or stopped, that is a separate state and should be diagnosed using version-specific Siemens requirements and service logs.

Verification

A successful verification identifies the actual server endpoint and obtains a server endpoint response from a local OPC UA client. Confirm that the WinCC server is running and that expected tags can be browsed/read according to the project's security and tag-exposure configuration. Do not treat presence of a discovery service, a green license indicator, or opening TCP port 4840 as proof that the WinCC runtime server is available.

Limitations and Operational Precautions

The root cause of the reported PCS 7 V9.0 SP2 system remains unproven: its OPC UA server component may have been absent, but no installed-component report, setup log or full version list is included. Siemens documents used here include a V7.4 SP1 example and a general WinCC OPC checklist; the PDFs returned HTTP 403 when opened, so this article relies on indexed manual content and does not claim to have inspected the full procedures. Exact PCS 7 V9.0 SP2 component selection and project activation steps need confirmation against its installation media and release documentation. Add software or change communication/security configuration only through the site's approved change process, with a backup and rollback plan.

Engineer FAQ

Is the WinCC OPC UA server enabled by default? The available Siemens V7.4 SP1 example says the server is integrated in V7.4 and available when the Connectivity Pack option package is installed and licensed; it does not establish default activation for every release or project.

Should OPC Scout browse opc.tcp://localhost:4840? Siemens identifies 4840 as the Local Discovery Server port; the WinCC V7.4 example gives 4862 as the default WinCC OPC UA server port. Browse the configured server endpoint.

What does a missing OpcUaServerWinCC service suggest? Check whether the WinCC OPC UA server component was installed in the matching release. The absence is a useful installation clue, not a complete root-cause diagnosis.

Does an active Connectivity Pack license prove the OPC UA server is installed? No. Licensing and installed software components are separate checks.

Should OPC DA DCOM advice be used for this OPC UA failure? No. OPC DA uses DCOM; OPC UA uses its own endpoint and security configuration. Follow the diagnostic path for the protocol actually in use.

Technical References

Siemens, WinCC 7.4 OPC UA Server—Excel Client, Entry ID 109752976, V1.0 (02/2018), §§1.2 and 2.6.2; specifies WinCC V7.4 SP1, Connectivity Pack installation/license, default server port 4862, and endpoint retrieval. Siemens PDF returned HTTP 403 when opened: https://support.industry.siemens.com/cs/attachments/109752976/109752976_OPC_UA-Excel_Client_WinCC_V7.4_en.pdf
Siemens, WinCC OPC Checklist, Entry ID 109763316, V1.0 (07/2019), §2.12; states classic WinCC V7 requires a Connectivity Pack license for its OPC UA server, while WinCC Professional has different licensing. Siemens PDF returned HTTP 403 when opened: https://support.industry.siemens.com/cs/attachments/109763316/109763316_WinCC_OPC_Checklist_en.pdf
Siemens, Ports and Protocols, identifies port 4862 for the WinCC OPC UA service and 4840 for the OPC UA Discovery Server: https://support.industry.siemens.com/cs/attachments/109963934/109963934_Ports_Protocols_V1_0.pdf

Troubleshoot WinCC OPC UA Discovery When the Server Is Missing