Recovering Corrupted Plant Hierarchies, Missing CFC Charts, and Symbol Tables After VM Crashes in PCS 7

When a virtual machine running a SIMATIC PCS 7 Engineering Station crashes abruptly due to host memory contention or power loss, database locks and uncommitted Sybase/SQL transaction logs can corrupt the project index. This causes the Plant Hierarchy to appear empty (showing only Shared Declarations) and CFC charts to vanish from Plant View and Component View, even though compiled DBs and FCs remain in the offline block folder. To recover the project, first close SIMATIC Manager and delete any orphaned 'lock' file inside the project's ApiLog directory, then execute 'Save As... with Reorganization (slow)' to rebuild relational pointers and symbol tables.

Anatomy of PCS 7 Project Database Corruption After Abrupt VM Termination

A SIMATIC PCS 7 project is not a single flat file; it is a complex relational database structure consisting of proprietary database tables (dBase/FoxPro .dbf files), Microsoft SQL Server databases (for WinCC), and Sybase ASA / SQL Anywhere databases that cross-link:
* The Plant Hierarchy (hrs): Manages the folder hierarchy, technological hierarchy levels, and assignment of charts to hierarchy folders.
* The Chart Container (chart.dbf, block.dbf): Manages CFC/SFC chart logic, block instances, parameters, and chart-to-chart interconnections.
* The Symbol Table (SYMLISTS): Maintains symbolic variable names, hardware addresses, and data types.
* The Block Folder (subproj.ini, *.s7p): Stores compiled binary S7 executable objects (DBs, FCs, FBs, OBs).

When a virtualization hypervisor (such as VMware Workstation, ESXi, or Microsoft Hyper-V) experiences severe memory contention, host operating system freeze, or sudden power termination while SIMATIC Manager is writing to disk, write buffers are severed mid-transaction. Relational header pointers become desynchronized, leaving the project structure in a corrupted, half-mounted state.

The Role of the ApiLog Lock File and Transaction Desynchronization

When SIMATIC Manager opens an engineering project, the internal STEP 7 database engine initializes a lock file inside the project's ApiLog directory:

<Project_Path>\<Project_Name>\ApiLog\lock

Normal Operation: When SIMATIC Manager or CFC editors access project files, this lock file signals to other background processes and network instances that the database is actively being modified. Upon a graceful shutdown of SIMATIC Manager, the transaction log flushes pending writes to disk, closes file handles, and automatically deletes the lock file.
Abrupt VM Crash: When the VM halts violently due to memory contention, the OS terminates without calling the clean-up routines. The lock file remains frozen on the virtual disk.
Subsequent Project Launch: When the user reboots the VM and opens SIMATIC Manager, the application reads the residual lock file. The database engine enters a fail-safe read-restricted or detached state. It cannot mount the Plant Hierarchy database (hrs) or parse the chart index (chart.dbf), resulting in the GUI rendering an empty plant tree displaying only the root "Shared Declarations" folder.

Symptom Analysis: Missing Plant Hierarchy and Invisible CFC Charts

Engineers encountering this corruption observe distinct diagnostic symptoms:
1. Empty Plant View: Navigating to View > Plant View shows no hierarchy folders. Only "Shared Declarations" appears.
2. Missing Charts in Component View: Navigating to View > Component View > SIMATIC 400 Station > CPU > S7 Program > Charts shows zero CFC or SFC charts.
3. Persisting Compiled Blocks: Navigating to the Blocks folder reveals that compiled Data Blocks (DBs) and Function Calls (FCs) originating from the missing CFC charts still exist in the offline block folder.
4. Desynchronized File Timestamps: Windows Explorer reveals that folders within the project directory have reverted to older file modification timestamps or display mismatched transaction dates due to uncommitted NTFS journal rollbacks during Windows crash recovery.

Primary Recovery Strategy: Removing Locks and Performing Reorganization

The first and most effective non-destructive recovery procedure targets clearing the orphaned lock and forcing a structural database rebuild:

Terminate All Siemens Processes: Completely shut down SIMATIC Manager, WinCC Explorer, and any background automation services (s7tgtopx.exe, s7oiehsx.exe, CCApp.exe).
Delete the ApiLog Lock File:
* Open Windows Explorer and navigate into the affected project directory:
C:\<Path_To_Multiproject>\<Project_Name>\ApiLog\
* Check for the presence of a file named lock (or lock.*).
* Delete the lock file permanently.
Execute 'Save As... With Reorganization (Slow)':
* Launch SIMATIC Manager and open the affected multi-project.
* In the main menu, click File > Save As....
* In the Save As dialog, select a new destination path or project name.
* Crucial Step: Check the box With Reorganization (slow).
* Click OK.
* Mechanism: Unlike standard fast saving which copies binary structures verbatim, "Save As with Reorganization (slow)" reads all database records sequentially, purges fragmented records, validates table integrity, recalculates relational cross-references between SYMLISTS and the hrs hierarchy, and rewrites the database cleanly into the new destination.

Advanced Recovery: Restoring Relational Tables and Symbol Lists

If reorganization fails because internal database tables are structurally truncated, advanced project surgery is required:

S7-Program Container Transplant:
If the plant hierarchy remains damaged but a recent project archive (.zip) or VM snapshot is available, you can open both projects side-by-side in SIMATIC Manager. Create a clean S7-Program container in the recovered project, copy the Chart container from the backup, and re-import any newly created block sources (.scl, .awl) created prior to the crash.
Symbol Table Recovery:
If the symbol table (SYMLISTS) is corrupted, navigate to Options > Symbol Table > Export in the backup project, export the symbols to a .dif or .csv file, and import them directly into the reconstructed project.
Restoring from ApiLog Shadow Copies:
In rare instances, inspecting <Project_Name>\ApiLog\ reveals transaction log files (.log) that contain the SQL journal entries of edits made immediately prior to the crash. Siemens Technical Support utilities can replay these journal files to reconstruct missing chart references.

Troubleshooting Matrix for PCS 7 Database Corruption Scenarios

The following table provides diagnostic guidelines and recovery paths based on project corruption symptoms:

Observed SymptomUnderlying Root CauseImmediate Corrective ActionPlant View empty; only 'Shared Declarations' visibleOrphaned lock file in ApiLog preventing hrs mountClose SIMATIC Manager, delete <Project>\ApiLog\lock, reopen projectCharts visible in Component View but missing in Plant ViewDisconnected plant hierarchy link (pcf.dbf)Reorganize project (Save As with Reorganization), or re-assign charts to hierarchyAll CFC charts missing; DB/FC blocks remain in Blocks folderCorrupted chart.dbf / missing chart container indexExecute Save As with Reorganization (slow); if unrecovered, restore from backupSymbol table shows empty grid or 'Database locked' errorCorrupted SYMLISTS index or active process lockKill background Siemens services via Task Manager; delete lock file; reorganizeError 'Project is locked by another user' upon openingLingering network lock file (*.ldb or ApiLog\lock)Delete lock file in project root and ApiLog subfolderCFC compile aborts with internal database errorOrphaned temporary files in wincproj or CFC cacheClose project, clear project temporary directory, execute complete reorganization

Step-by-Step Reorganization and Recovery Walkthrough

Follow this verified engineering procedure to recover a crashed PCS 7 project:

Quarantine the Damaged Project Folder:
* Prior to making any modifications, create a complete zip archive copy of the damaged project folder to ensure an immutable snapshot exists.
Clear Orphaned Lock Files:
* Navigate to D:\Projects\<My_Project>\ApiLog\.
* Delete lock. Also check the subproject folders (\wincproj\, \Global\) for any *.ldb or *.lck files and delete them.
Open and Verify Project State:
* Open SIMATIC Manager. Open the multi-project.
* If prompted with "The project was not closed properly", allow the system to perform internal checks.
Perform Deep Reorganization:
* Select File > Save As....
* Browse to a clean directory on a local drive with ample free space (avoid network shares).
* Enter a new project name (e.g., Project_Recovered).
* Select the radio button With Reorganization (slow).
* Click OK and allow the reorganization to proceed (may take 10 to 45 minutes for large multi-projects).
Verify Hierarchy and Recompile:
* Open the newly saved project.
* Switch to Plant View and confirm that all technological hierarchy folders, CFC charts, and SFC charts are fully visible.
* Open the Symbol Table and verify tag mappings.
* Perform a CFC Compile > Entire Program to re-establish dynamic block cross-references.

Verification

Verify that project integrity is completely restored using the following diagnostic checks:
1. Open Plant View and navigate through all hierarchy levels down to individual technological units, ensuring every CFC and SFC chart opens without error dialogs.
2. Open the Symbol Table in the S7 Program container and verify that symbolic addresses match the I/O addresses defined in HW Config.
3. Execute Options > Reference Data > Display in CFC; verify that the cross-reference list generates cleanly without reporting missing block instances or dangling interconnections.
4. Perform a complete CFC compilation (Scope: Entire program). Ensure compilation completes with 0 Errors.
5. In WinCC Explorer, verify that the OS project opens cleanly and that the OS compilation wizard successfully reads the restored plant hierarchy tags.

Limitations and Operational Precautions

Backup Discipline: No automated repair utility can replace a disciplined multi-project archiving strategy. Always execute File > Archive (.zip) prior to major engineering changes, and configure automated VM hypervisor snapshots during inactive hours.
VMware Memory Contention Safeguards: To prevent VM freezes, configure Memory Reservation in VMware Workstation or ESXi settings, guaranteeing dedicated host physical RAM to the Engineering Station VM. Disable Windows dynamic pagefile ballooning on drives hosting automation projects.
Never Edit DBF Files Directly: Never attempt to modify project .dbf or .hrs files using external database editors (such as Microsoft Access or FoxPro). Direct manual edits invalidate internal hash signatures and permanently corrupt the project structure.
Commercial Accuracy: In the event of catastrophic data loss requiring engineering recovery services, Siemens Technical Support provides specialized database repair contracts. Procure hardware and support entitlements through an authorized Siemens distributor quotation.

Engineer FAQ

Can I retrieve my lost CFC logic by disassembling the compiled DB and FC blocks?

No. In SIMATIC PCS 7, compiled DBs and FCs contain only binary machine code and raw variable instances; they do not contain the graphical layout, comments, signal interconnections, or runtime group structuring present in the CFC charts. The original chart database (chart.dbf) is required to edit the program in CFC.

Why does 'Save As with Reorganization (slow)' take so much longer than a standard Save As?

Standard Save As performs a simple file-level copy. Reorganization (slow) parses every individual record across dozens of relational database tables, reorganizes physical indexes on disk, strips deleted record flags, and reconstructs damaged structural pointers, which is an intensive database operation.

What should I do if deleting the ApiLog lock file does not restore the Plant Hierarchy?

If deleting the lock file fails, the hrs database tables are physically truncated. Restore the project from the most recent .zip archive or VM snapshot. If recent unarchived work was completed, copy the compiled blocks and source files into a new project shell created from the backup.

How can I prevent VMware from freezing and corrupting PCS 7 projects?

Configure 100% memory reservation for the VM, store virtual disks on high-performance enterprise SSDs (RAID 10 or NVMe) with write-caching protected by battery-backed write cache (BBWC), and ensure VMware Tools is kept updated.

Technical References

Related Tags

Database Recovery
Plant Hierarchy
ApiLog Lock
CFC Corruption
VMware Crash
Reorganization

Recovering Corrupted Plant Hierarchies, Missing CFC Charts, and Symbol Tables After VM Crashes in PCS 7