Filtering Simulation, Override, and Bypass Messages in SIMATIC PCS 7 CEMAT

In SIMATIC PCS 7 systems utilizing the CEMAT minerals and cement industry library, filtering out non-critical operational messages such as Simulation, Override, and Bypass signals is accomplished by configuring WinCC AlarmControl SQL selection criteria, customizing CEMAT message classes in the engineering system, or tailoring the CEMAT configuration file (C_CONFIG.CFG). By isolating maintenance status flags from active process fault classes, control room operators maintain visibility over high-priority equipment trips without nuisance message flooding during commissioning or maintenance overrides.

CEMAT Alarm Architecture and Message Routing

The SIMATIC PCS 7 CEMAT library utilizes specialized control blocks—such as C_DRV_1D (unidirectional drive), C_DRV_2D (bidirectional drive), C_VALVE (damper/valve), and C_MEASUR (measured value processing)—to manage heavy industrial equipment. Each CEMAT technological block incorporates integrated signal supervision routines that detect when an input channel is switched into software simulation (SimAct), maintenance bypass (Bypass), or local override mode.

Under factory default configurations, switching a drive into simulation or placing an interlock in bypass generates an operational message via the underlying ALARM_8P mechanism. While essential for field technicians during plant commissioning, continuous alarm generation for operational overrides creates visual clutter in runtime alarm lists. CEMAT structures messages into distinct classes and user text blocks within the WinCC Alarm Logging database, enabling granular filtering without disabling underlying diagnostic logging.

Configuring WinCC AlarmControl Filters for Maintenance States

To suppress or isolate Simulation and Bypass messages within runtime alarm displays, engineers can establish dedicated SQL selection filters within the WinCC AlarmControl object:

Open WinCC Graphics Designer: Open the primary alarm screen (typically @AlarmActive.pdl or a custom operational overview).
Access AlarmControl Properties: Double-click the WinCC AlarmControl object and navigate to the Message Selection tab.
Define Selection Criteria: Click Edit to launch the SQL filter builder.
Filter by Message Class or Text:
- To filter by text string: Set criteria where Text2 (Message Text) or Text3 does not contain Simulation AND does not contain Bypass.
- To filter by Message Class: Reassign override messages to the System - Without Acknowledgment or Operational Message class, then uncheck that specific class in the operational alarm view.
Assign Filter to Toolbar Functionality: Link the filter configuration to a dedicated toggle button on the WinCC operator toolbar, enabling operators to switch between 'Clean Operations View' and 'Maintenance/Override Audit View' with a single click.

Customizing CEMAT Block Message Classes in CFC

Where filtering at the runtime client level is insufficient, the alarm generation behavior can be modified directly within the CFC engineering environment:

Open Master Data Library: Access the technological block types in the project library.
Configure Block Message Properties: Double-click the C_DRV_1D or C_MEASUR block instance in CFC, open the Messages dialog, and locate the specific message identifier assigned to Simulation.Override (typically SIG 7 or SIG 8).
Reassign Message Class: Change the class from Alarm High to Status Message or Maintenance Prompt. This prevents the event from triggering audible horns or locking active fault banners.
Suppress Event Generation via Block Inputs: Many CEMAT modules provide dedicated control parameters (such as MSG_EN or parameter bits in the STATUS word) to completely disable message generation for simulated signals when hardware safety systems take precedence.
Compile OS: Perform a changes-only OS compilation to propagate updated alarm attributes to the WinCC server package.

Comparison of CEMAT Message Filtering Methods

The following table compares architectural methods for filtering simulation and bypass signals in SIMATIC PCS 7 CEMAT:

Filtering MethodConfiguration LevelEngineering EffortOperator ImpactAudit Trail PreservedWinCC AlarmControl SQL FilterOS Runtime Client ScreenLow (Minutes)Immediate dynamic toggle between operational and maintenance viewsYes (Events remain in short-term and long-term archive)CEMAT C_CONFIG.CFG ParameterizationOS Server / Client ScriptsMediumGlobal suppression across standard CEMAT faceplatesYes (Logged to hard disk message log files)CFC ALARM_8P Class ReassignmentAS Engineering StationMedium-High (Requires OS Compile)Alters event severity and horn routing permanentlyYes (Archived under reassigned message category)Hardware Parameter Bit SuppressionAS CFC InterconnectionHigh (Requires AS Download)Prevents event creation entirely at controller execution levelNo (Events are completely suppressed at AS source)

Note: In safety-critical cement and mining applications, never suppress bypass events permanently at the AS block level without implementing secondary audit procedures.

Verification

Verify CEMAT message filter functionality using the following steps:
1. In CFC test mode, force the simulation input (SimAct = 1) on a test drive instance (C_DRV_1D).
2. Confirm in WinCC Runtime that the active operational alarm screen (@AlarmActive.pdl) suppresses the simulation event when the filter is enabled.
3. Open the WinCC Long-Term Archive or Journal List and verify that the simulation entry is logged with timestamp, user ID, and tag identifier.
4. Toggle the AlarmControl filter button and verify that the simulation message appears immediately in the Maintenance Audit view.

Limitations and Operational Precautions

Applying message suppression filters carries significant process safety considerations:
- Never filter emergency trip bypasses from central maintenance logs; unmonitored overrides may allow equipment to operate outside physical safety boundaries.
- Modifying standard CEMAT library block message structures directly can break consistency when updating to subsequent CEMAT service packs. Always maintain customizations within the Master Data Library.
- OS compilations overwrite client-level filter scripts if custom SQL selection strings are not embedded into the base project template or picture user scripts.

Engineer FAQ

Can CEMAT faceplates show simulation status if messages are filtered?

Yes. The CEMAT faceplate symbol and icon display a yellow simulation icon or letter 'S' driven directly by the block status word (STATUS), independent of whether the event message is visible in the alarm banner.

Where is the CEMAT C_CONFIG.CFG file located?

The file is located in the OS project directory under Cemat\Config\C_CONFIG.CFG or within the root multiproject directory structure, depending on the CEMAT version.

Does filtering bypass messages prevent them from transferring to Process Historian?

No. WinCC AlarmControl filters only affect visual presentation on the HMI screen. All messages generated by ALARM_8P continue to flow through the alarm cache to Process Historian.