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Resolving WinCC Error 'No Connection to Data Server' - Alarm Logging Runtime and DCF File Cleanup

Resolving WinCC Error 'No Connection to Data Server' - Alarm Logging Runtime and DCF File Cleanup

When WinCC AlarmControl in SIMATIC PCS 7 OS Runtime displays the persistent error message 'No connection to data server' ('Keine Verbindung zum Datenserver') and scripts or faceplates become unresponsive, the root cause is a communication breakdown between the graphic runtime and the internal WinCC Alarm Logging database engine (CCAlgRtServer.exe). To eliminate this error, execute three primary remediation actions: first, open WinCC Explorer -> Computer Properties -> Startup tab and ensure that 'Alarm Logging Runtime', 'Tag Logging Runtime', and 'Global Script Runtime' are checked; second, close WinCC, navigate to the OS project directory, and delete the temporary project cache file <ProjectName>.dcf (which WinCC regenerates automatically upon reopening); third, verify that the OS computer name matches the physical Windows computer name and that the Standard Server for Alarms and Split Screen Manager (SSM) is assigned.

Table of Contents

Architectural Anatomy of the WinCC 'Data Server' in SIMATIC PCS 7

In SIMATIC PCS 7 OS (WinCC Runtime), the graphical operator interface does not communicate directly with controller hardware; instead, it communicates through internal background subsystems called Data Servers:

  • Alarm Logging Data Server (CCAlgRtServer.exe): Manages the message queue, incoming alarms, operator acknowledgments, and alarm archive storage in Microsoft SQL Server.

  • Tag Logging Data Server (CCTlgRtServer.exe): Manages real-time process value archiving and historical trend queries.

  • Graphic Runtime (PdlRuntime.exe / WinCCExplorer.exe): Hosts the WinCC AlarmControl embedded in @alarm.pdl and process pictures.

When the operator opens an alarm screen and observes the banner 'No connection to data server' ('Keine Verbindung zum Datenserver'), the AlarmControl ActiveX/.NET control is signaling that inter-process communication (IPC) via DCOM or SQL Server sockets to CCAlgRtServer.exe has failed or timed out.

Root Causes: Inactive Runtime Services, DCF File Locks, and Name Mismatches

Field troubleshooting reveals five primary failure modes that trigger this error:

  1. Unchecked Startup Applications: In WinCC Explorer Computer Properties, if the Alarm Logging Runtime checkbox was inadvertently deselected, WinCC activates Graphics Designer without starting the background alarm database engine.

  2. Corrupted Project Cache (<ProjectName>.dcf): The .dcf file caches local computer names, server package GUIDs, and network endpoints. Following an unclean shutdown, engineering station conversion (e.g., converting an ES to an ES/OS Single Station), or network card replacement, stale GUIDs in the .dcf lock data server handshakes.

  3. Computer Name Mismatch: If the physical Windows computer name was changed or differs from the name defined under Computer in WinCC Explorer, runtime services fail to resolve the local server handle.

  4. Corrupted Archive Segments: If SQL Server archive files (*.mdf) became corrupted or locked during a power loss, CCAlgRtServer hangs during database attachment.

  5. Missing Standard Server Assignment on OS Clients: On distributed clients, if the client does not know which server handles alarms, the alarm banner remains disconnected.

The Critical Role of the Project Configuration File (.dcf)

The <ProjectName>.dcf file (located directly in the WinCC project root directory) is a temporary SQLite/relational cache file used by WinCC to track active station properties, communication channels, and redundancy states:

  • When WinCC crashes or is terminated via Windows Task Manager, the .dcf file frequently retains stale process locks and orphaned station IDs.

  • Safe Deletion Protocol: The .dcf file contains no user programming, graphics, or archive data. When WinCC is closed, deleting <ProjectName>.dcf is completely safe. Upon reopening WinCC Explorer, the system automatically rebuilds a fresh, pristine .dcf file from the master project database (<ProjectName>.mdf), instantly clearing corrupt pointers.

Standard Server Assignments for Split Screen Manager (SSM) and Alarms

On OS Clients and Multi-Clients, alarms and Split Screen Manager (SSM) utility functions require an explicit server destination:

  • In WinCC Explorer, right-click Server Data -> select Standard Server...

  • Ensure that the component Alarms and component SSM (Split Screen Manager) are assigned to a valid, active OS Server package.

  • If these fields are set to 'No server', the client's alarm controls will display 'No connection to data server' because no routing target exists.

Comparative Fault Diagnostic Matrix: 'No Connection to Data Server'

The following table compares root causes, symptoms, and corrective actions for WinCC data server disconnects:

Root CauseDiagnostic IndicatorVerification LocationCorrective ActionAlarm Logging Runtime inactiveAlarms blank; graphics updateWinCC Computer Properties -> StartupCheck 'Alarm Logging Runtime'; restart RuntimeCorrupted <ProjectName>.dcf file'No connection' on all controls; scripts hangWinCC Project DirectoryClose WinCC; delete <ProjectName>.dcf; restart WinCCComputer Name MismatchWinCC prompts 'Computer name does not match'Control Panel System vs WinCC ComputerUpdate WinCC computer name to match Windows hostnameMissing Standard Server on ClientClients show error; Server operates normallyWinCC Explorer -> Server Data -> Standard ServerAssign valid OS Server package to Alarms & SSMCorrupted SQL Archive SegmentSQL Server Event Log error 823/824Windows Event Viewer -> ApplicationRun CCArchiveManager.exe -reset all via Run promptOrphaned Server Data PackagesRed cross on Server Data iconWinCC Explorer -> Server DataDelete old .pck files; re-import fresh packages

Step-by-Step Procedure to Restore Data Server Communication and Purge Cache

Follow this comprehensive procedure to resolve 'No connection to data server':

  1. Deactivate Runtime and Close WinCC:
    - Deactivate WinCC Runtime cleanly.
    - Close WinCC Explorer and SIMATIC Manager.

  2. Purge Corrupted <ProjectName>.dcf File:
    - Open Windows Explorer and navigate to your WinCC project directory (e.g., D:\Projects\OS_PRJ\).
    - Locate the file <ProjectName>.dcf (e.g., OS_SRV.dcf).
    - Delete this file (or rename it to OS_SRV.dcf.bak).

  3. Verify Computer Name in WinCC:
    - Reopen the project in WinCC Explorer.
    - Confirm that WinCC automatically rebuilds the .dcf file.
    - In the project navigation tree, click Computer.
    - Verify that the computer name listed on the right matches the physical Windows computer name exactly (case-sensitive).

  4. Verify Startup Applications:
    - Right-click the computer name -> Properties -> Startup tab.
    - Ensure the following checkboxes are enabled:

    • Alarm Logging Runtime
    • Tag Logging Runtime
    • Global Script Runtime
    • Click OK.

  5. Reset Archives if Database Corruption Suspected:
    - If the error persists, press Win + R, type: CCArchiveManager.exe -reset all, and press Enter.
    - This purges corrupted active archive buffers while preserving closed historical segments.

  6. Assign Standard Server (For OS Clients):
    - On OS Clients, expand Server Data -> right-click Standard Server...
    - Set Alarms and SSM to the primary OS Server package.

  7. Re-run OS Project Editor and Test Runtime:
    - Run OS Project Editor to refresh system templates.
    - Activate WinCC Runtime. Confirm that the AlarmControl initializes with full connection to the data server.

Verification

Verify data server restoration through these validation checks:

  1. Activate WinCC Runtime. Observe the startup progress dialog: confirm that 'Alarm Logging Runtime' and 'Global Script Runtime' initialize.
  2. Open the main alarm overview screen (@alarm.pdl).
  3. Confirm that the error banner 'No connection to data server' is completely gone.
  4. Trigger a process alarm or toggle a test digital input. Confirm that the alarm appears in the active incoming list within 1 second.
  5. Click an interactive block icon and verify that the technological faceplate opens immediately and responds to operator clicks.

Limitations and Operational Precautions

  • CCArchiveManager -reset all Data Impact: Running CCArchiveManager -reset all clears the active runtime database segment. It is an emergency diagnostic tool; always back up ArchiveManager folders before executing an archive reset.
  • Never Delete .mdf Files Manually: Deleting <ProjectName>.dcf is completely safe, but never delete <ProjectName>.mdf or <ProjectName>_RT.mdf, as doing so permanently deletes the WinCC configuration and runtime databases.
  • Redundant Server Synchronization: If one server in a redundant pair displays this error, redundancy synchronization will pause. Resolve the data server failure immediately to prevent historical archive drift between partners.

Engineer FAQ

Is it safe to delete the <ProjectName>.dcf file?

Yes, 100% safe. The .dcf file is a temporary cache file that WinCC automatically regenerates from the master SQL database upon opening the project.

Why did faceplates stop responding when this error appeared?

Faceplate operations and script actions require Global Script Runtime and the Alarm Logging subsystem. When the data server connection breaks, WinCC pauses script execution to prevent inconsistent data writes.

Can network firewall rules cause 'No connection to data server'?

Yes. On OS Clients, if Windows Firewall blocks DCOM (TCP 135) or dynamic RPC ports, the client cannot communicate with the server's CCAlgRtServer.exe process.

What does CCArchiveManager.exe -reset all do?

CCArchiveManager.exe -reset all detaches and cleans corrupted active logging segments in Microsoft SQL Server, allowing the logging engines to start with fresh, healthy database segments.

Why did converting my ES to an ES/OS Single Station cause this error?

Converting an ES project to an ES/OS Single Station alters the project type from Multi-User to Single-User. The cached .dcf file still expected a remote server package. Deleting the .dcf file re-registers the project as a local Single Station.

Technical References

Related Articles

Related Tags

  • WinCC AlarmControl
  • No Connection to Data Server
  • DCF File
  • Alarm Logging
  • CCArchiveManager
  • Project Cache
  • PCS 7 OS
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