Resolving the OS Compilation Warning - 'The Chart Folder of S7 Program Has Not Been Compiled' in SIMATIC PCS 7

The warning message 'The chart folder of S7 program [AS_Name\AS_Prog] has not been compiled' during SIMATIC PCS 7 OS compilation occurs because the AS-OS Engineering Compiler requires an up-to-date compiled CFC chart database to extract technological tags, alarm structures, and block icons. The OS compiler does not parse graphical CFC sheets directly; instead, it extracts metadata from the compiled symbol and instance DB tables. If changes were made to CFC charts without executing a CFC compile prior to starting the OS compile, the compiler flags the chart folder as uncompiled. To resolve this warning, open CFC Editor and execute 'CFC > Compile > Entire program' (or 'Changes only'), then re-run the OS compile.

The AS-OS Compilation Pipeline: Relational Dependencies Between CFC and WinCC

In SIMATIC PCS 7, the core engineering advantage is automated integration between the Automation Station (AS) and the Operator Station (OS). Instead of manually creating WinCC tags, scaling analog values, and configuring alarm limits line-by-line, the AS-OS Engineering Compiler scans the S7 Program for function blocks marked for Operator Control and Monitoring (S7_m_c := 'true') and automatically populates the WinCC tag management, alarm logging, and picture tree databases.

However, this automation relies on a strict sequential dependency pipeline:

Hardware Configuration (HW Config): Defines physical I/O addresses, CP communication processors, and symbolic rack layouts.
Network Configuration (NetPro): Defines S7 Named Connections between the AS CPU and the WinCC OS Application.
CFC / SFC Compilation: Compiles graphical charts into executable S7 machine code (FBs, FCs, DBs), generating the central chart reference data.
AS-OS Compilation: Reads the compiled chart reference data and transfers tags, messages (ALARM_8P), and archive definitions into the OS.

Why the OS Compiler Evaluates Compiled Chart Headers Rather Than CFC Graphics

When an engineer clicks Compile OS in SIMATIC Manager, the compiler does not inspect raw graphic drawing files (*.cfc). Reading graphic sheets directly across hundreds of charts would be extraordinarily slow.

Instead, the AS-OS compiler queries the compiled binary headers and cross-reference tables in the Step 7 database:

It inspects the Compilation Time Stamp of the S7 Program's chart folder.
If the chart folder has never been compiled, or if an engineer opened a CFC chart, made logic or parameter adjustments, and saved without compiling, Step 7 flags the chart folder as 'Compilation required'.
When the OS compiler runs, it detects this flag and generates the compilation log warning:

'Warning *: The chart folder of S7 program AS01\AS01_Prog has not been compiled.'

The OS compile completes, but it extracts data from the last compiled state, meaning newly added blocks or modified faceplate tags will not appear in WinCC OS.

Root Causes: Out-of-Order Compilation and Stale Time Stamps

This warning commonly arises in three standard engineering workflows:

New AS Station Creation: An engineer inserts a new SIMATIC 400 station, creates the Plant Hierarchy, and configures an OS project, then immediately executes an Entire OS Compile to test network communication before authoring or compiling CFC logic.
Independent Team Engineering: In multi-user projects, an HMI engineer compiles the OS while an automation engineer is actively editing CFC charts without compiling changes.
S7 Program Renaming: Renaming the S7 Program folder (e.g., from S7 Program(1) to AS01_Prog) resets internal database timestamps, requiring a fresh CFC compile to synchronize reference tables.

Eliminating Dependency Warnings via 'Compile and Download Objects'

To eliminate out-of-order compilation errors across large multiprojects, Siemens provides the 'Compile and Download Objects' utility in SIMATIC Manager:

Accessible via menu PLC > Compile and Download Objects...
The utility presents a centralized tree view of all AS and OS stations in the multiproject.
It automatically enforces correct compilation sequencing: it compiles Hardware Configuration first, compiles Connections in NetPro second, compiles CFC/SFC charts third, and compiles the WinCC OS fourth.
Using this automated sequence guarantees that all prerequisite chart databases are fully up to date before the OS compiler extracts tags.

Comparative Dependency Matrix: CFC Compilation vs OS Compilation

The following table compares the scope, artifacts, and execution order of CFC and OS compilation in SIMATIC PCS 7:

Compilation StageInput ArtifactsGenerated Output ArtifactsPrimary Compiler ToolImpact if Skipped1. CFC CompilationGraphical CFC/SFC ChartsS7 FBs, FCs, DBs, Chart Reference DataCFC Compiler (SCL/STL)CPU logic not updated; OS warning generated2. AS-OS CompilationCompiled Chart Reference Data + SymbolsWinCC Tags, Alarms, Archives, Block IconsAS-OS Engineering CompilerWinCC OS out-of-sync with controller logic3. Block Icon UpdateOS Process Pictures + TypicalsBlock Icons instantiated in *.pdlPlant Hierarchy CompilerGraphic screens lack equipment block icons4. Server Data PackageCompiled OS Database<OS_Name>.pck Server PackageWinCC Server Data GeneratorOS Clients cannot view OS Server tags

Step-by-Step Procedure to Clear Compilation Warnings

Follow this procedure to resolve the uncompiled chart folder warning:

Compile CFC Charts First:
- In SIMATIC Manager, expand the target AS station: SIMATIC 400 > CPU > S7 Program > Charts.
- Open any CFC chart.
- Select menu CFC > Compile > Changes only (or select Entire program if compiling a new station).
- Ensure the compiler finishes with 0 Errors, 0 Warnings.
Verify Chart Folder Status:
- In SIMATIC Manager Component View, right-click the Charts folder -> Object Properties.
- Check the Version tab: confirm that the compilation timestamp reflects the current time.
Execute OS Compilation:
- In SIMATIC Manager, select the target OS Server project.
- Right-click and select Compile OS (or PLC > Compile and Download Objects...).
- In the wizard, select the S7 Program AS01\AS01_Prog and select Changes only (or Entire OS).
- Complete the wizard. Confirm that the compilation log finishes with 0 Warnings and 0 Errors.
Update Block Icons in Process Pictures:
- Right-click the Plant Hierarchy folder -> Plant Hierarchy > Create/Update Block Icons.
- Verify that any newly compiled blocks have their corresponding block icons generated cleanly.

Verification

Validate compiler synchronization through these checks:

Open the OS compilation log file (compile.txt in the OS project directory).
Verify that the warning string 'The chart folder has not been compiled' is completely absent.
In WinCC Explorer, open Tag Management. Verify that newly added CFC blocks appear under the S7 Named Connection tag group.
Open WinCC Graphics Designer. Verify that block icons display correct tag bindings without red cross broken links.

Limitations and Operational Precautions

Ignoring the Warning: If an engineer ignores the warning and downloads the OS to runtime, the OS will run, but any new blocks or modified parameters added in CFC will show disconnected gray faceplates or trigger WinCC tag read errors.
Multi-AS Projects: In multiprojects with multiple automation stations (e.g., AS01, AS02, AS03), all assigned AS programs must be compiled in CFC before running an Entire OS compile; otherwise, warnings will be reported for each uncompiled station.
Runtime Downloads: Compiling CFC and OS can be performed while the plant is operational, but downloads must follow standard 'Changes Download' procedures.

Engineer FAQ

Why did the OS compile finish successfully if there was a warning?

The OS compiler treats an uncompiled chart folder as a non-fatal warning rather than a hard abort. It compiles using the last valid compiled state of the AS program.

Can I compile the OS without compiling CFC if I only made changes in WinCC Graphics Designer?

If you only edited graphic pictures (*.pdl) in Graphics Designer, you do not need to compile the OS or CFC at all! Picture edits are saved directly in the OS project.

What is the difference between 'Changes Compile' and 'Entire Compile' in OS compilation?

'Changes Compile' only transfers newly added or modified blocks, tags, and alarms, completing in seconds. 'Entire Compile' rebuilds the entire OS tag database from scratch and should be used during initial commissioning or structural database cleanups.

Why does 'Compile and Download Objects' fail if an editor is open?

Step 7 requires exclusive file locks during compilation. If a CFC chart, HW Config, or WinCC Explorer is actively open and editing data, the compiler will abort with access conflict errors.

Does compiling CFC automatically trigger an OS compile?

No. CFC compilation updates the controller code. You must initiate OS compilation separately or use the automated 'Compile and Download Objects' tool.