WinCC V7 Tag Logging Not Working: CCTlgServer Crash Fix

Problem Overview

Symptom: A WinCC V7 project reads all PLC tags correctly into graphics, but the Tag Logging runtime produces no values. Online Trend Control and Online Table Control windows are empty or display a single "u." character in each row. Process values that were configured as archive tags are simply not being persisted, and CCTlgServer.exe — the Tag Logging server process — either fails to start at runtime or terminates immediately when launched manually. This is one of the most reported failure modes on WinCC V7.0 / V7.2 stations, and it is independent of the underlying PLC connection (TCP/IP, MPI/PROFIBUS, S7-Plus, OPC, or named connections are all affected equally).

The reporting case in the project log shows 420 PLC tags being polled successfully while Tag Logging remains dead, which immediately rules out a tag-licensing issue for process tags (PowerTags) and points instead at the archive-tag license, the Tag Logging runtime service, or the archive configuration itself.

Root Cause Analysis

WinCC V7 separates process tags (read from the PLC) from archive tags (written to the Tag Logging database). When the Tag Logging service is missing from the startup list, the process crashes, or the archive configuration is corrupt, the trend/table controls have nothing to display even though the graphics layer is fully functional. The five root-cause families observed in the field are:

1. TagLogging runtime not started — CCTlgServer.exe is missing from the computer startup list in the WinCC project properties.
2. Archive-tag license exceeded — the project uses more than the licensed number of archive tags; the runtime refuses to start the affected archive without producing a hard error.
3. CCTlgServer.exe crash on startup — corrupt archive configuration, missing SQL database, or invalid tag reference causes the process to exit immediately.
4. Process tag ↔ archive tag mismatch — graphics and tag logging read different tag objects, or archive tags were never linked to process tags.
5. Trend/Table control not bound to the right archive — the control is associated with the wrong archive, the wrong time range, or the wrong column name.

WinCC V7 Licensing Architecture

WinCC V7 uses two independent license counters. Both are managed by the Siemens Automation License Manager (ALM) and both must be sufficient before runtime data is logged.

Diagnostic rule of thumb: if the project reads more than 128 PLC tags on graphics, a PowerTag license upgrade is already required; if more than 512 process tags are referenced inside a Tag Logging archive, an additional archive tag license is required. In the case under analysis, 420 process tags are read successfully, which exceeds the 128 PowerTag limit and at the same time exceeds the default 512 archive-tag limit only if all 420 tags are also placed in the archive. Always count archive tags in the Tag Logging editor, not process tags in the tag management.

CCTlgServer.exe Process Diagnostics

The Tag Logging server is implemented as a Windows process CCTlgServer.exe. It is a child of CCExpMgr.exe (the WinCC Runtime main process) and starts only when the WinCC project is in runtime.

1. Open Task Manager → Details on the WinCC server.
2. Sort by image name and look for CCTlgServer.exe.
3. If the process is not present while runtime is active, Tag Logging is either not in the startup list or has crashed at startup.
4. Try launching it manually from <WinCC install>\bin\CCTlgServer.exe. If the window opens and closes within one second, the archive configuration is corrupt.
5. Inspect <ProjectPath>\<ComputerName>\WinCCProject.ldf and <ProjectPath>\<ComputerName>\TagLogging\*.txt for the last load error.

Tag Logging Activation in the Startup List

The Tag Logging runtime is an opt-in component. It is not started automatically just because a Trend control exists on a screen. The activation is done in the WinCC Explorer:

1. Open WinCC Explorer on the engineering station or the server.
2. Right-click Computer in the project tree and select Properties.
3. Switch to the Startup tab.
4. Enable Tag Logging Runtime in the Additional Tasks / Applications list and set its startup delay (default 0 s; for stations with large archives use 10–20 s to allow the SQL database to mount first).
5. Click OK, save the project, and reload on the runtime station.

If the checkbox is greyed out, the WinCC project is open on another station (the project database is locked). Close the project on the engineering station before editing the startup list on the server.

Archive Configuration in the Tag Logging Editor

Tag Logging requires three consistent objects: a Tag Logging archive, a process tag supply, and a column definition. The typical failure pattern is that the archive exists, the process tag is reachable, but the column is not bound.

1. Open Tag Logging in WinCC Explorer.
2. Right-click Archives → Archive Wizard. The wizard creates a new archive backed by the project SQL database (default instance: \<ComputerName>\WinCC).
3. For each archive, open the Properties dialog and verify:
   • Archive type: Tag Logging (process-value archive) — not Alarm Logging.
   • Storage location: the configured path is on a local drive with at least 10 % free space; avoid network shares.
   • Backup settings: a backup path is configured and the backup drive is reachable.
   • Size limit: a sensible ring-buffer size (e.g. 500 MB) is set, or segmentation by time is enabled.
4. Add a Tag to the archive and bind it to a process tag (Tag Logging → Archives → <Archive> → Tags → right-click → Add Tag).
5. Define the Acquisition cycle (how often the process tag is polled) and the Archiving cycle (how often the polled value is persisted). The archiving cycle must be an integer multiple of the acquisition cycle. A common mistake is to set both to 1 s; this generates 86 400 rows per tag per day and will quickly fill a 500 MB ring buffer.
6. For event-driven archives, configure a Trigger (Boolean process tag edge, OPC event, or scheduler). Without a trigger, the archive will not write at all even if the acquisition cycle is correctly set.

Online Trend Control and Online Table Control Status Indicators

Both control types have a small status row in their on-screen toolbar. Two monitor icons appear on the right side of that row:

If only the right icon is red, the failure is local to the Tag Logging service. The Online Table Control showing a single letter "u." in every cell indicates the same condition: the column is bound to an archive that is not supplying data.

Reconnect Procedure for Archive Tags

Stale references between process tags and archive tags are a frequent source of empty trend windows. The reconnect is performed in the WinCC Explorer without restarting the project:

1. Open the WinCC project on the runtime server (close the project on the engineering station first).
2. Right-click Tag Logging → Update. This forces a re-link between the process tag namespace and every archive tag.
3. Right-click Tag Management → Update. The AS-OS connection is rebuilt.
4. Stop the runtime, then restart it. Verify CCTlgServer.exe remains in the process list for at least 30 seconds.
5. Open a Trend window and confirm the right-hand monitor icon turns green.

Database Considerations

WinCC V7 stores archive data in an embedded Microsoft SQL Server instance. The instance name is WinCC and the database is named after the project. The default storage path is <ProjectPath>\<ComputerName>\<ProjectName>.mdf.

1. Open SQL Server Management Studio and connect to \.\WinCC with Windows authentication.
2. Confirm the project database exists and its status is Normal. A database in Suspect or Recovery Pending will block CCTlgServer.exe from opening the archive and may crash the process at start.
3. Check the disk volume holding the database files: WinCC requires continuous free space. When the disk is full, the SQL instance detaches the database and Tag Logging stops writing.
4. Verify the SQL Server service account has Read/Write/Modify on the project folder. If the WinCC project was copied from another machine, the original owner is preserved and the local SQL service may fail to attach the database.
5. On V7.0, the default SQL Server is SQL Server 2005 (32-bit). On V7.2 and later the default is SQL Server 2008 R2 (32-bit). Mismatched SQL versions after a backup-restore cycle are a common cause of CCTlgServer.exe exiting immediately.

User Rights and Windows Security

The WinCC runtime service must run under a user that is a member of the local group SIMATIC HMI and that owns the project directory. The TagLogging service inherits the rights of its parent CCExpMgr.exe. Symptoms of insufficient rights include CCTlgServer.exe starting, briefly showing a console window, and then exiting without a log entry.

1. Open Computer Management → Local Users and Groups → Groups → SIMATIC HMI.
2. Confirm the user that starts the WinCC runtime is a member of this group.
3. On the project directory, grant Modify to SIMATIC HMI and to the runtime service user.
4. Disable UAC for the runtime service user, or use the supplied SIMATIC HMI WinCC Explorer shortcut that runs elevated.

Time Synchronisation and Timestamp Quality

Tag Logging writes the timestamp of the local WinCC station. If the local clock drifts relative to the PLC, the row will be persisted but the trend will appear empty because the time range filter on the control excludes the time the row was written.

1. On the WinCC server, run w32tm /query /status and confirm the time source.
2. Enable the WinCC time synchronisation service so the server itself is the NTP/SNTP master for the project (Computer Properties → Parameters → Time Synchronisation).
3. If the server synchronises to a domain controller, verify the DC is reachable and that the WinCC service account has the right to read time from the DC.
4. Re-open the trend control, set the time range to "Last 5 minutes", and confirm rows now appear.

Recommended Upgrade Path: V7.0 SP3 Update 8

The reported case was opened against WinCC V7.0.2. The recommended corrective upgrade is V7.0 SP3 plus Update 8. Key facts:

• Upgrade package order number: S79220-B3611-P (V7.0 SP3 incl. Update 1, on installation DVD).
• Update 8 is delivered as a downloadable hotfix and does not require a new license when the customer already owns a valid WinCC V7.0 license.
• The hotfix covers several known TagLogging defects, including archive corruption after a power loss, incorrect handling of the 512-archive-tag boundary, and the silent CCTlgServer.exe exit on stations with multiple language OS settings.
• The hotfix is documented in Siemens support entry 109741127.
• After installation, perform a full project recompile (WinCC Explorer → right-click project → Rebuild) and re-transfer the project to the runtime station.

Customers on WinCC V7.2 should apply Update 14 or later. The TagLogging service architecture is identical, and the same diagnostics apply.

Step-by-Step Recovery Procedure

1. Stop the WinCC runtime on the server and back up the project directory.
2. Open the project on the engineering station.
3. Computer → Properties → Startup → enable Tag Logging Runtime with a 10 s delay.
4. Open Tag Logging and confirm each archive has at least one column, every column is bound to a valid process tag, and the archiving cycle is a positive integer multiple of the acquisition cycle.
5. Open Automation License Manager and verify the archive-tag license count covers the configured archive tags (count from Tag Logging → Archives → each archive → Tags).
6. If the project is on V7.0, apply V7.0 SP3 Update 8 per Siemens KB 109741127.
7. Rebuild the project (right-click project → Rebuild).
8. Transfer to the server, start runtime, and verify CCTlgServer.exe stays alive in Task Manager for at least 60 seconds.
9. Open a Trend window and confirm the right-hand monitor icon is green and that the trend trace contains data points.
10. If the right-hand icon is still red, switch the SQL database to simple-recovery, shrink the database, and restart the WinCC runtime.

Verification Checklist

Troubleshooting Matrix

Field-Proven Caveats

• Applying V7.0 SP3 to an existing project does not change the archive-tag count but does reset the licence hash; re-activate the licence in ALM before the first runtime start, otherwise the runtime starts in grace mode for 14 days and then stops writing archives.
• On Windows 10/11 stations, the SQL Server (WinCC) instance must run in SQL Server 2008 R2 compatibility mode. The default instance of SQL Server 2012 or higher is not compatible with WinCC V7.0.
• If the project was migrated from a different station, the RegIniPath in the project computer list must be updated, or CCTlgServer.exe will try to read the archive configuration from the original computer path and crash.
• Do not run two WinCC runtimes against the same project directory simultaneously. The second CCTlgServer.exe will fail to lock the SQL database and exit silently.
• Online Trend Control's "Common online configuration" must reference the same archive name on every client. Renaming the archive after a Trend control is configured produces an empty trend even on the engineering station.

FAQ