C135 PCS 7 (PCS7)
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Troubleshooting SFC Editor Crashes During OS Comment Editing and Version Compatibility in PCS 7

Troubleshooting SFC Editor Crashes During OS Comment Editing and Version Compatibility in PCS 7

Sequential Function Chart (SFC) editor crashes during condition creation or OS comment editing in SIMATIC PCS 7 V9.0 SP2 are caused by software component regressions in early compiler builds. Attempting to resolve editor crashes by installing unreleased or mismatched components—such as installing SFC V9.0 SP5 from PCS 7 V9.1 or SFC V9.0 SP7 from V9.0 SP3—breaks binary compatibility with underlying STEP 7 and CFC subsystems. The correct engineering solution is to upgrade the Engineering Station to the fully validated PCS 7 V9.0 SP3 maintenance baseline and install approved cumulative update collections.

Table of Contents

Mechanisms of SFC Editor Component Crashes in PCS 7

In SIMATIC PCS 7, Sequential Function Charts (SFC) provide phase and state logic execution for batch processes and automated sequences. The SFC editor (s7jsfcax.exe) coordinates tightly with the Continuous Function Chart (CFC) engine, the STEP 7 symbol table, and the WinCC Operator Station compilation interface:

  • OS Comment Synchronization: When an engineer edits step or transition properties and enters "OS Comments", the SFC editor calls internal COM objects to register text variables into the multilingual project dictionary (s7amx.dbf and project text tables).
  • Compiler Memory Index Bug in V9.0 SP2: Early builds of SFC V9.0 SP2 contained an internal buffer overrun defect within the string formatting subsystem. When a user created a transition condition and immediately attempted to modify the OS Comment field, the unhandled memory exception crashed s7jsfcax.exe.
  • Subsequent Session Lockout: Because the application terminates abnormally without executing cleanup handlers, the project database retains the active user lock, displaying the message "The SFC chart is already being edited by " upon reopening.

The Risks of Cross-Version Software Mixing

When confronted with crashes, engineers sometimes attempt to install newer individual components extracted from different PCS 7 distributions (e.g., extracting SFC V9.0 SP5 from PCS 7 V9.1, or installing SFC V9.0 SP7 from V9.0 SP3 into a V9.0 SP2 system). This practice introduces severe operational hazards:

  1. Binary COM Interface Incompatibilities: PCS 7 components (STEP 7, CFC, SFC, TH, BATCH) are compiled against shared C++ runtime DLLs and schema definitions. Installing an SFC package intended for PCS 7 V9.1 on a V9.0 SP2 station results in unresolved dynamic link library (DLL) imports, causing the editor to fail to launch entirely.
  2. CFC-SFC Cross-Compilation Failures: Even if the editor opens, subsequent chart compilations fail with internal errors (e.g., Error 1739:20 or compiler memory exceptions) because the CFC compiler and SFC generator utilize mismatched internal database structures.
  3. Loss of Siemens Support Validation: A system running mixed, uncertified component versions cannot be supported by Siemens Technical Support, as it violates the certified PCS 7 release compatibility matrix.

Step-by-Step Diagnostic and Crash Log Collection

If an SFC crash occurs, gather definitive diagnostic telemetry before altering software versions:

  1. Launch SIMATIC Assessment Suite (SAS):
    * Open the Start menu and launch SIMATIC Assessment Suite - Data Collector (formerly known as SIMATIC Diagnostics Tool / SDT).
    * Select Standard Diagnostics and initiate data collection.
    * SAS packages Windows Event Viewer Application logs, Siemens crash logs (s7asr*.log), and installed software version inventories into a compressed .zip archive for Siemens Technical Support analysis.
  2. Inspect Windows Application Event Log:
    * Open Windows Event Viewer (eventvwr.msc).
    * Navigate to Windows Logs -> Application.
    * Locate the Error entry timestamped with the crash. Confirm faulting application s7jsfcax.exe and record the faulting module name (e.g., s7jsfc*.dll or ntdll.dll) and exception code (0xc0000005 Access Violation).

Standardized Upgrade and Patch Recovery Procedure

To resolve the crash cleanly while preserving software compatibility and certification:

Step 1: Elevate to PCS 7 V9.0 SP3 Baseline

  1. Instead of piecemeal hotfixes, download the official SIMATIC PCS 7 V9.0 SP3 Update Collection or full Service Pack 3 upgrade.
  2. Close all engineering tools and run reset_wincc.vbs.
  3. Execute the unified PCS 7 Setup to elevate the entire engineering environment (STEP 7, CFC, SFC, WinCC) to V9.0 SP3.

Step 2: Apply Cumulative SFC Update Collection

  1. On the SIOS portal, locate the latest cumulative update for SFC on V9.0 SP3 (e.g., SFC V9.0 SP3 Upd2 or higher).
  2. Download and install the update. Cumulative updates on the matched Service Pack resolve the OS comment buffer overrun without causing COM conflicts.
  3. Restart the Engineering Station.

Clearing Orphaned SFC Editing Locks

Following an abnormal crash, the SFC chart must be unlocked before work can resume:

  1. Ensure SIMATIC Manager and all engineering sub-windows are closed across all network stations.
  2. Open Windows Task Manager and verify that no orphaned s7jsfcax.exe or s7jcfcax.exe processes remain running in the background.
  3. Launch SIMATIC Manager.
  4. Select the project in the tree, then select File -> Save As....
  5. Check With Reorganization (Slow), provide a temporary destination path, and execute the reorganization.
  6. The reorganization clears the dangling session lock flag, enabling clean read/write access to the chart.

Verification

Confirm that the SFC editor functions reliably:

  1. OS Comment Modification Test:
    * Open the previously failing SFC chart.
    * Create a new step and transition condition.
    * Enter text into the OS Comments field and click outside the box.
    * Confirm that the editor saves the string without crashing.
  2. Consistency and Compilation Check:
    * Select Chart -> Check Consistency. Confirm 0 errors.
    * In SIMATIC Manager, execute a program compilation (Charts -> Compile -> Changes only).
    * Verify that the compiler generates S7 executable code cleanly.

Limitations and Operational Precautions

  • Strict Adherence to Compatibility Tool: Never install individual component service packs without verifying compatibility using the online Siemens Compatibility Tool.
  • Multiproject Homogeneity: All Engineering Stations contributing to the same multiproject must be updated to the identical Service Pack and Update level.
  • Lab vs Production Separation: Never experiment with unreleased component updates on an active production engineering station.

Engineer FAQ

  • Why does the SFC editor crash specifically when editing OS comments?
    Early builds of SFC V9.0 SP2 contained a string buffer overrun in the text translation interface that triggered an access violation when editing OS comments.
  • Is it safe to install SFC V9.0 SP5 on a PCS 7 V9.0 SP2 engineering station?
    No, SFC V9.0 SP5 belongs to PCS 7 V9.1 and introduces binary DLL mismatches that can break compilation and prevent the editor from launching.
  • What is the official Siemens utility for collecting crash diagnostic logs?
    The SIMATIC Assessment Suite (SAS) - Data Collector, which automatically gathers Windows logs, Siemens traces, and software inventories.
  • How do I unlock an SFC chart that reports 'already being edited by ' after a crash?
    Verify that background processes are closed in Task Manager, then perform a 'Save As... With Reorganization (Slow)' in SIMATIC Manager.
  • Can I resolve the SFC crash by upgrading to PCS 7 V9.0 SP3?
    Yes, PCS 7 V9.0 SP3 and its cumulative updates resolve the OS comment memory fault across the entire integrated engineering suite.
  • Does editing an OS comment in SFC require compiling the WinCC OS?
    Yes, OS comments entered in SFC steps and transitions are transferred to WinCC operator displays during an OS compilation.
  • Where are SFC crash logs located on the local disk?
    Crash traces are typically written to C:\ProgramData\Siemens\Automation\Logfiles\ or within the STEP 7 user log directory.
  • What exception code typically indicates a memory buffer crash in Windows Event Viewer?
    Exception code 0xc0000005 (Access Violation), which signifies that an application attempted to read or write unallocated memory.
  • Can corrupted symbol tables cause SFC editor crashes?
    Yes, if an SFC chart references a deleted symbol or invalid technological hierarchy folder, opening properties can trigger compiler crashes.
  • What is the difference between an SFC Chart and an SFC Type in PCS 7?
    An SFC Chart is an individual technological sequence instantiated directly in an AS, whereas an SFC Type is a reusable template that can be instantiated across multiple equipment phases.

Technical References

  • Siemens Industry Online Support (SIOS) Portal: How do you efficiently collect diagnostics and system information with the SIMATIC Assessment Suite? (Entry ID: 65976201).
  • SIMATIC PCS 7 SFC for S7 Programming Manual, Siemens AG.
  • Siemens Compatibility Tool for Automation and Drive Technology.

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Related Tags

PCS 7, SFC, Crash, Troubleshooting, Software Compatibility, SIMATIC Assessment Suite, S7JCFCAX, STEP 7

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