Troubleshooting Missing CEMAT Long-Term Archive Alarms Across Multiple PLCs in PCS 7

In SIMATIC PCS 7 systems running the CEMAT minerals and cement library across multiple automation stations, an issue where alarms and warnings from only one PLC appear in the WinCC long-term archiving list is typically caused by unassigned message archive flags, incomplete OS compilation with memory reset, or misaligned CEMAT system parameters (ARCHIV_LANG). Restoring uniform long-term archiving across all controllers requires verifying CEMAT message classes, executing a full OS compilation, and ensuring historical message logging filters encompass all configured plant hierarchy areas.

Architecture of CEMAT Alarming and Long-Term Archiving in PCS 7

In heavy process industries (cement, mining, minerals), the SIMATIC PCS 7 CEMAT library extends standard PCS 7 architectures with specialized technological blocks (C_DRV_1D, C_DRV_2D, C_DAMPER, C_ANNUNC) designed for high-availability material handling.

In a multi-PLC CEMAT architecture (e.g., 9 automation stations connected to a central redundant OS Server pair):
* Operational Lists vs. Archive Lists: The operational list shows recent plant events and operator interventions. The Long-Term Archive List stores historical process alarms, warnings, and system faults in Microsoft SQL Server database partitions for regulatory compliance and downtime auditing.
* Message Class Propagation: Each CEMAT block relies on standardized ALARM_8P message definitions linked to specific CEMAT event classes (Faults, Warnings, Operational Interventions, Interlocks).

Root Causes: Why Multiple PLCs Fail to Populate the Historical Archive

When alarms from only one PLC appear in the long-term archive while the remaining eight PLCs display only operational messages, three underlying defects are typically responsible:

1. Incomplete OS Compilation and Unsynchronized Message Classes

If OS compilation was executed incrementally for Station 1 without performing an OS Full Compilation with Memory Reset across the Multiproject, the message archive property flags for Stations 2 through 9 remain unassigned in the WinCC Alarm Logging database.

2. CEMAT System Parameter Inconsistency (`ARCHIV_LANG` / `C_CONFIG`)

CEMAT features global configuration parameters that govern whether messages from specific controller sub-systems are routed to long-term archiving. If the configuration block in Stations 2–9 omits the archive flag, events bypass long-term SQL partitions.

3. Alarm Logging Message Class Filter Restrictions

In WinCC Alarm Logging, message classes assigned to CEMAT faults must have the Archive checkbox explicitly checked. If the archive property is active only for a single AS area, the remaining PLCs will only display active status without entering historical storage.

Step-by-Step Procedure: Realigning CEMAT Message Archiving

Verify Block Message Definitions in CFC:
* In SIMATIC Manager, open a sample CFC chart in Station 2 containing C_DRV_1D.
* Open block properties -> Messages: verify that message numbers and text definitions are populated and match Station 1.
Configure WinCC Alarm Logging Message Classes:
* Open WinCC Explorer on the OS Server.
* Open Alarm Logging.
* Navigate to Message Classes -> CEMAT Alarms / Warnings.
* Right-click properties: ensure that Archive is selected for all relevant message types.
Execute OS Full Compilation with Memory Reset:
* In SIMATIC Manager, right-click the OS Server and select Compile.
* Select all 9 Automation Stations.
* Under compilation options, choose Entire OS and select With memory reset.
* Run the compilation to regenerate all message configuration records.
Synchronize Server Redundancy:
* Download the compiled OS to both redundant OS servers.
* Restart WinCC Runtime sequentially to align database structures.

Verification

Trigger a simulated test alarm on a motor drive (C_DRV_1D) in Station 2 and Station 9.
On the WinCC OS screen, click the CEMAT Long-Term Archive List button.
Verify that alarms from both Station 2 and Station 9 appear chronologically in the archive grid alongside Station 1.
Filter by plant area: verify that all 9 PLC hierarchy areas return historical event records.

Limitations and Operational Precautions

Memory Reset Precaution: Performing an OS compilation with memory reset restores standard block message texts; ensure any custom block messages were configured in the Master Data Library (MDL) rather than directly in WinCC.
Server Disk Space: Enabling historical archiving for 9 high-capacity PLCs significantly increases SQL database growth; monitor Tag Logging and Alarm Logging archive segment limits.
CEMAT Version Consistency: Ensure all 9 PLCs run identical CEMAT library versions and service packs.

Engineer FAQ

What is the function of the CEMAT Long-Term Archive list?
It provides historical query and auditing capabilities for alarms, warnings, and faults stored in SQL Server.
Why did operational messages appear while alarms were missing in the archive?
Operational messages use distinct message classes that were assigned to the local buffer but lacked archive flags.
Does compiling the OS with memory reset delete historical alarm records?
No, memory reset clears only configuration cache tables; historical runtime archives in SQL Server remain intact.
Which CEMAT block manages single-direction drives?
The C_DRV_1D function block controls and monitors single-direction motor drives.
Can CEMAT alarms be filtered by technological plant area?
Yes, WinCC Alarm Control allows operators to filter records by plant hierarchy area.
What causes block icons to display alarm symbols when the archive list is empty?
Block icons reflect real-time AS status bits, whereas the archive list queries historical SQL records.
Do CEMAT blocks consume standard PCS 7 AS Process Objects?
Yes, technological blocks with OCM and alarm capabilities consume AS and OS Process Objects.
How are alarm texts edited in CEMAT projects?
Texts should be modified in the Master Data Library CFC block types prior to compilation.
Does CEMAT require a dedicated software license?
Yes, the SIMATIC PCS 7 CEMAT library requires specific engineering and runtime licenses in ALM.
Where should CEMAT software package upgrade paths be verified?
All CEMAT library versions and compatibility matrices must be validated in the Siemens Industry Mall.

Technical References

Siemens Manual: SIMATIC PCS 7 Minerals and Mining CEMAT System Manual (A5E44583210-AA).
Siemens Industry Online Support Entry ID 109801081: CEMAT Message System and Alarm Logging Guide.
WinCC V7.4 / V7.5 Alarm Logging Configuration Manual.