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Disabling Alarm Generation on Valve Blocks and Suppressing Area Button Indications in SIMATIC PCS 7 WinCC

Disabling Alarm Generation on Valve Blocks and Suppressing Area Button Indications in SIMATIC PCS 7 WinCC

To suppress alarm generation and visual area button alerts from valve control blocks in SIMATIC PCS 7, engineers can either disable message classes at the Continuous Function Chart (CFC) block level or apply runtime alarm locking in WinCC. Selecting No message in the CFC block message configuration permanently prevents the automation station from dispatching ALARM_8P telegrams to the operator station. Alternatively, operators can suppress active visual alerts on WinCC area overview buttons by applying runtime message locking or configuring alarm state filters within the WinCC Alarm Logging editor.

Table of Contents

Alarm Generation Architecture in PCS 7 Valve Blocks

In SIMATIC PCS 7, valve control function blocks—such as standard valve FB73 (VALVE) or Advanced Process Library (APL) blocks VlvL and Vlv2Way—rely on integrated message blocks (ALARM_8P) to report equipment discrepancies, feedback errors, and interlock trips:

  • ALARM_8P Subsystem: The block encapsulates message IDs that bind process conditions (e.g., feedback opening timeout, feedback closing timeout, electrical fault, interlock active) to pre-defined message classes (Alarm High, Warning, Tolerance, System Message).
  • AS-to-OS Message Flow: When an error condition asserts in the controller, ALARM_8P packages the timestamp, message ID, and associated process values into an S7 communication frame dispatched over the Industrial Ethernet plant bus to the WinCC OS Server.
  • WinCC Message System and Area Overview (CSIGArea): WinCC Alarm Logging receives the message, writes it to the active circular message archive, and evaluates the technological area assigned to the block via the Plant Hierarchy. The WinCC area overview buttons (AreaButtons in the @Overview1.pdl screen) update dynamically, illuminating visual alarm or warning banners based on collective area alarm states.

Disabling Alarms at the CFC Block Message Configuration Level

To permanently suppress alarm transmission for a specific valve block without modifying underlying SCL or block code:

  1. Open SIMATIC Manager and navigate to the target Continuous Function Chart (CFC).
  2. Double-click or right-click the target valve block (e.g., FB73 or VlvL) and select Object Properties.
  3. In the Object Properties window, click the Messages... button to launch the PCS 7 Message Configuration editor.
  4. The dialog displays all message identifiers assigned to the block (e.g., SIG1: Feedback error opening, SIG2: Feedback error closing, SIG3: Interlock).
  5. In the Message Class column for the undesired alarms, click the drop-down menu and select <No message>.
  6. Click OK to close the message configuration dialog, then click OK in Object Properties.
  7. Save the CFC chart.
  8. Execute an OS Compilation (PLC -> Compile and Download Objects -> OS Compile) selecting Changes only to propagate the stripped message configuration to the WinCC database.

Suppressing Area Overview Button Indications in WinCC OS

If alarms must continue to be logged in the historical journal but should not highlight the collective area overview buttons in the WinCC title bar (CSIGArea / AreaButtons):

  1. Open WinCC Explorer on the Engineering Station.
  2. Open the Alarm Logging editor.
  3. Locate the specific message rows corresponding to the valve tag.
  4. In the message properties table, inspect the Message Class:
    * Standard alarm classes (Alarm, Warning) are configured by default to trigger the collective area indication hierarchy.
    * Reassign the message class to an informational class (such as System without Acknowledgment or a custom operator message class) that does not participate in the area overview sum calculation.
  5. In OS Project Editor, navigate to the Message Display tab:
    * Verify which message classes are linked to the collective display flags.
    * Deselect any message class that should be excluded from collective area button illumination.

Applying Runtime Alarm Locking from WinCC Faceplates

If alarm suppression is temporary (e.g., during equipment maintenance, instrument flushing, or manual valve testing), use runtime alarm locking rather than modifying engineering configurations:

  1. In WinCC Runtime, navigate to the valve graphic symbol and click it to open the standard APL faceplate.
  2. If using standard APL, click the Alarm View button or the Lock / Unlock button in the faceplate toolbar.
  3. With sufficient operator authorization (typically Level 5 or Level 6), click the Lock Messages button.
  4. The automation station driver asserts the block's internal message lock flag (MsgLock = 1 or MsgEn = 0).
  5. While message locking is active:
    * No new alarms are generated or dispatched to WinCC.
    * The valve block icon displays a distinct message lock symbol (crossed-out bell or wrench icon).
    * Active area overview button indicators for that block immediately extinguish.
  6. Once maintenance concludes, operators click Unlock Messages to restore full monitoring.

Verification

Confirm that alarm generation and area button behavior conform to expectations:

  1. Controller-Level Suppression Check:
    * Induce a test feedback fault (e.g., command the valve to open while holding feedback inputs closed).
    * Verify that the valve block enters the fault state locally in CFC Test Mode without generating an ALARM_8P transmission error.
  2. WinCC Alarm List Verification:
    * Inspect the WinCC Alarm Logging runtime list.
    * Confirm that no incoming alarm event is registered for the configured valve tag.
  3. Area Overview Button Verification:
    * Verify that the corresponding area button in the top banner (@Overview1.pdl) remains neutral and does not illuminate red (Alarm) or yellow (Warning).

Limitations and Operational Precautions

  • Regulatory and Functional Safety Risks: Never suppress alarms on emergency shutoff valves or interlocked safety components without a formal management-of-change (MOC) review.
  • Re-Compilation Overwrite: If alarms are modified directly within WinCC Alarm Logging rather than via CFC Object Properties, subsequent full OS compilations will overwrite local WinCC settings with the CFC database definitions.
  • Process Object License Impact: Suppressing individual messages via <No message> does not decrease the Process Object (PO) licensing consumption of the valve block; PO counting depends on block instances rather than active alarm count.

Engineer FAQ

  • What happens when I set a CFC block message to ''?
    The CFC compiler removes the message definition from the block instance, preventing the controller from dispatching ALARM_8P telegrams to WinCC for that specific signal.
  • Can I disable alarms on a valve block from WinCC Runtime without re-compiling the project?
    Yes, operators with appropriate security credentials can use the faceplate 'Message Lock' function to suppress alarms dynamically during runtime.
  • Why does the area button in WinCC continue to flash after fixing the valve fault?
    The alarm message class requires operator acknowledgment; until the cleared event is acknowledged in the alarm list, the collective area button maintains flashing or steady alarm indications.
  • Does setting '' remove the message from all valve blocks in the project?
    No, configuring messages via CFC Object Properties applies strictly to that specific individual block instance.
  • How does PCS 7 determine which area button corresponds to a specific valve?
    PCS 7 maps block instances to area overview buttons based on the Plant Hierarchy folder structure assigned to the CFC chart.
  • Where is the collective area display logic configured in WinCC?
    In the WinCC OS Project Editor under the 'Message Display' and 'Areas' tabs, which configure the CSIGArea and AreaButtons graphical objects.
  • Can I suppress warnings while keeping critical trip alarms enabled on the same valve?
    Yes, in the CFC Messages dialog, you can selectively set non-critical signals (e.g., SIG2: Warning) to '' while retaining SIG1 (Trip Alarm).
  • Does locking alarms on a valve block prevent safety interlocks from closing the valve?
    No, message locking only suppresses alarm messaging and visual alerts; controller interlock logic (Intlock, Protect) remains fully operational.
  • Why did my custom WinCC Alarm Logging modifications disappear after compiling the OS?
    A full OS compile synchronizes WinCC Alarm Logging with the CFC engineering database; any modifications made exclusively in WinCC without updating CFC will be overwritten.
  • What user authorization level is required to lock alarms in APL faceplates?
    By default, APL faceplates require Process Controlling rights (Authorization Level 5) or Higher Process Controlling (Level 6) to lock messages.

Technical References

  • Siemens Industry Online Support (SIOS) Portal: How do you configure messages for blocks in SIMATIC PCS 7? (Entry ID: 23742444).
  • SIMATIC PCS 7 Operator Station Engineering Manual (V9.0 / V9.1), Siemens AG.
  • SIMATIC PCS 7 Advanced Process Library (APL) Function Manual, Siemens AG.

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Related Tags

PCS 7, WinCC, Alarm Logging, APL, Valve Block, FB73, Message Configuration, Area Buttons

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