C135 PCS 7 (PCS7)
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Resolving Missing Client Operation Messages in WinCC Alarm Logging for PCS 7 OS Clients

Resolving Missing Client Operation Messages in WinCC Alarm Logging for PCS 7 OS Clients

In SIMATIC PCS 7 multi-user architectures (such as CEMAT or standard APL server-client configurations), when operator actions performed on OS Servers are properly recorded in WinCC Alarm Logging but operations executed from OS Clients fail to register in the Operation List (Bedienmeldungen), the failure is caused by an unassigned Standard Server for Alarms on the OS Client. OS Clients do not maintain local alarm archives; instead, they route operator messages across the Terminal Bus to a designated server archive. If the Standard Server for 'Alarms' is not specified in the client WinCC configuration, client-side operator actions cannot be directed to any server message archive and are dropped. To resolve the issue, open Server Data in WinCC Explorer on the OS Client, open the Standard Server dialog, assign the redundant OS Server pair as the Standard Server for Alarms, and restart runtime.

Table of Contents

Executive Summary

Regulatory frameworks (such as FDA 21 CFR Part 11 and industrial audit standards) mandate that all manual process interventions—such as setpoint adjustments, mode switches, and motor start/stop commands—must be permanently recorded in an electronic audit trail. In distributed PCS 7 systems, these audit events are captured as Operator Input Messages (Bedienmeldungen). While server consoles record local events seamlessly, newly staged or reconfigured OS Clients frequently suffer from silent audit omissions where client operations vanish from alarm logs. Assigning the Standard Server for Alarms establishes the required message routing pathway between client operator actions and central server historical archives.

Architecture and Fundamental Mechanics

The message routing and client-server archiving architecture in WinCC operates through defined communication pathways:

  1. The Client-Server Message Architecture:
    * In a PCS 7 multi-user system, historical archive databases (Alarm Logging and Tag Logging) reside exclusively on the redundant OS Servers.
    * OS Clients operate as thin visualization nodes; they hold no local SQL message archives.
  2. The Generation of Operator Messages (Bedienmeldungen):
    * When an operator modifies a parameter on an APL faceplate (e.g., clicking 'Manual' on a valve), the faceplate script invokes internal system functions to generate an operator input message (Message Class 17 / 'Operation').
    * This message payload contains the timestamp, operator user name, computer name, old value, new value, and tag name.
  3. The Standard Server Routing Requirement:
    * For standard process alarms generated in the AS, the controller sends messages directly to the server that compiled its OS connection.
    * However, for client-generated operator messages, the client WinCC runtime kernel (CCAlgRtServer) must know which server's message system should receive and archive the event.
    * If the Standard Server for Alarms is unassigned (<No standard server>), the client message dispatcher cannot resolve an archive destination and discards the message packet, preventing it from appearing in any server or client alarm control.

Step-by-Step Implementation Procedure

Follow these procedures to configure the Standard Server for Alarms on the OS Client in WinCC Explorer or SIMATIC Manager:

  1. Method 1: Configure Standard Server in WinCC Explorer (Direct OS Client Setup):
    * On the physical OS Client (or ES in Client view), open the target OS Client project in WinCC Explorer.
    * In the navigation tree, locate and expand Server Data.
    * Right-click Server Data and select Standard Server....
    * In the Configure Standard Server dialog, locate the component row labeled Alarms.
    * Click the drop-down menu in the Symbolic computer name column and select the symbolic name of your redundant OS Server pair (e.g., OS_SRV_PRJ_OS(1)).
    * If using Split Screen Manager or SIMATIC BATCH, also verify standard server assignments for SSM and BATCH.
    * Click OK to commit the settings.
  2. Method 2: Configure in SIMATIC Manager (Engineering Station Workflow):
    * On the ES, open SIMATIC Manager in Component View.
    * Navigate to the OS Client station object and expand the WinCC application.
    * Right-click the OS Client object and select Open Object.
    * Under Server Data, right-click and select Standard Server....
    * Assign the redundant OS Server pair for Alarms.
    * Close WinCC Explorer on the ES and execute a Target OS Download (PLC > Download) to the OS Client machine.
  3. Restart WinCC Runtime on the OS Client:
    * On the OS Client, deactivate WinCC Runtime if currently active.
    * Re-activate WinCC Runtime.
    * The client message kernel binds to the server alarm service.

Verification

On the OS Client, open a process graphic containing an APL motor or valve faceplate. Modify a setpoint or toggle the operational mode from Auto to Manual. Immediately open the WinCC Alarm Logging display (Operation List / Bedienmeldungen tab). Verify that a new entry appears showing the timestamp, the client computer name in the 'Computer' column, the operator username, and the parameter change details.

Limitations and Operational Precautions

In multi-server systems with partitioned plant areas, all client operation messages will be directed to whichever server is designated as the Standard Server for Alarms; ensure that the selected server has adequate SQL archive capacity. Never leave the Standard Server unconfigured on multi-client installations.

Engineer FAQ

Why did server operations log successfully while client operations failed?

The OS Server automatically routes local events to its own local alarm archive; OS Clients require an explicit Standard Server configuration to route events across the network.

What components require a Standard Server in PCS 7?

Typically 'Alarms' (for operator messages) and 'SSM' (Split Screen Manager for screen navigation) require standard server assignments.

Does changing the Standard Server require restarting WinCC Runtime?

Yes. The client alarm dispatcher initializes server endpoints during runtime startup; a runtime restart is required for changes to take effect.

What WinCC message class corresponds to operator actions?

Message Class 17 (Operation / Bedienmeldung) represents manual operator interventions.

Technical References

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Related Tags

  • WinCC Alarm Logging
  • OS Client
  • Standard Server
  • Bedienmeldungen
  • Operator Messages
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