How to Remove Stale Non-Acknowledgeable PCS 7 OS Messages Without Restarting Runtime

For a PCS 7 V9.0 OS message that no longer corresponds to an existing event and cannot be acknowledged, Siemens provides Entry ID 109751476: add its DeleteAlarm process display, compile the OS, then use its AlarmControl in WinCC Runtime to remove selected stale messages with a comment. The Siemens procedure applies to PCS 7 V9.0, V9.1 and V10.0 and is specifically for non-acknowledgeable messages no longer present. It does not authorize clearing a genuinely active alarm.

When the procedure applies

The reported symptom is a crossed-out or persistent entry in the pending-message view after its AS block was deleted, on PCS 7 V9.0 SP1 with redundant OS servers and five clients. Siemens' procedure applies when an alarm-system message is no longer present but cannot be acknowledged, and describes removing that message without restarting the OS. Confirm that the selected entry is truly stale and no longer has an active source before deleting it. If the process condition is still active, resolve the source condition through the normal alarm-handling path.

Prerequisites and preparation

Use Siemens Industry Online Support Entry ID 109751476 and its version-matched sample project 109751476_DeletePendingMessage_PROJ_PCS7V90.zip. The current Siemens document identifies PCS 7 V9.0, V9.1 and V10.0 (and WinCC) as applicable. Have the correct project open on the configuration computer and make a recoverable project archive before modifying its plant hierarchy. Identify the OS area hierarchy level: Siemens requires the DeleteAlarm screen to be copied there. Do not confuse the sample-project display with the active target OS project.

Install the DeleteAlarm screen

Copy the Siemens sample project ZIP to the configuration computer. 2. In SIMATIC Manager, choose File > Dearchive, select 109751476_DeletePendingMessage_PROJ_PCS7V90.zip, choose a storage folder, and open the extracted project. 3. Switch to Plant View and open the target project in parallel. 4. Copy the DeleteAlarm screen from the sample project DelSelMes_Proj into the target project's Technological Hierarchy at the hierarchy level configured as the OS area. 5. Compile the OS after adding the screen. These steps follow Siemens Entry ID 109751476. Use the provided sample as published for the applicable PCS 7 release; do not modify unrelated project objects.

Delete selected stale messages in Runtime

Activate the target project's OS (WinCC Runtime). 2. Open the added DeleteAlarm process display. 3. In its WinCC AlarmControl, select the non-acknowledgeable message confirmed to be obsolete. 4. Click Delete selected message. 5. Enter an explanatory text in the Comment on message dialog and click OK. 6. Repeat only for additional confirmed stale messages. Siemens states that this removes the selected message from the PCS 7/WinCC message system and creates an archive note that records its removal. The comment provides traceability for the operator action.

Remove the temporary display

After the message cleanup, delete the DeleteAlarm screen from the target project's Technological Hierarchy and recompile the OS, as Siemens instructs. Confirm the project's normal compile and deployment workflow for its redundant OS architecture before transferring changes. The Siemens article's purpose is removing non-acknowledgeable messages without restarting the OS; follow its detailed sample and the project's approved procedure rather than substituting a full OS memory-reset compile.

Expected results and active alarms

A successfully deleted selected stale message is removed from the PCS 7/WinCC message system, while an archive note records the removal and supplied comment. The support article does not state that deleting a still-active alarm is equivalent to acknowledging or clearing its underlying condition, and it does not establish exactly when such an alarm will reappear. Therefore, use the function only for messages no longer present in the process/message source. A real active alarm must remain subject to the plant's alarm response and acknowledgement rules.

Verification

Before deletion, correlate the alarm's origin, event text and state with the AS/project configuration to confirm that the associated source event no longer exists. Afterward, confirm the selected message is absent from the current message system and that the removal/comment note is recorded in the archive. Then remove DeleteAlarm, compile the OS as documented, and confirm the intended Runtime/project state across the redundant OS arrangement using the installation's controlled transfer procedure.

Limitations and Operational Precautions

Entry ID 109751476 targets non-acknowledgeable messages that are no longer present. It does not establish a general method for suppressing active process alarms, cleaning arbitrary Alarm Logging data, or deleting historical archive records. Removing an entry from the current message system is distinct from removing its archive history; Siemens explicitly says an archive note is created. The source discussion's statement that deleting a truly active message suppresses it until a new edge is not confirmed by the Siemens procedure cited here, so do not rely on that behavior. Because the target has redundant OS servers, make and verify project backups and use the applicable redundant OS compile/deployment procedure.

Engineer FAQ

Can I remove a stale message without restarting WinCC Runtime? Yes. Siemens Entry ID 109751476 documents a DeleteAlarm display for removing selected non-acknowledgeable messages without restarting the OS. Does the procedure apply to PCS 7 V9.0 SP1? Siemens lists PCS 7 V9.0, V9.1 and V10.0; the sample project is named for PCS 7 V9.0. What gets deleted? The selected message is removed from the PCS 7/WinCC message system; Siemens says an archive note records that removal. Should I delete an alarm that is still active? No. The documented case is a message no longer present and not acknowledgeable; the procedure does not establish safe handling of an active process condition. What must be done after cleanup? Remove the temporary DeleteAlarm screen from the project hierarchy and recompile the OS.

Technical References

Siemens, How do you delete a non-acknowledgeable message in PCS 7 OS Runtime or WinCC?, Industry Online Support Entry ID 109751476, current document Version 01/2025, procedure pp. 3–5; applies to PCS 7 V9.0/V9.1/V10.0 and WinCC. https://cache.industry.siemens.com/dl/files/476/109751476/att_941134/v5/109751476_DeletePendingMessage_DOC_en.pdf
Siemens Industry Online Support Entry ID 109751476 landing page: https://support.industry.siemens.com/cs/ww/en/view/109751476

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How to Remove Stale Non-Acknowledgeable PCS 7 OS Messages Without Restarting Runtime