Synchronizing Master Data Library Block Types to Enable CFC Delta Downloads in PCS 7

Errors during CFC compilation and downloading changes when adding APL blocks (such as Pcs7AnIn or MotL)—while simple elementary blocks compile without error—occur because the APL block types in the project offline block folder mismatch the versions loaded in the online CPU or Master Data Library. APL blocks invoke module drivers and diagnostic blocks (@-charts) that enforce strict interface consistency. To resolve this and restore delta downloading in RUN mode, execute 'Options -> Block Types...' in SIMATIC Manager to update all block types from the Master Data Library into the project, perform a block cleanup, and recompile CFC changes with 'Generate module drivers' enabled.

CFC Block Type Management and Delta Download Dependencies

In SIMATIC PCS 7, the Continuous Function Chart (CFC) compiler supports online delta downloading (Download Changes), allowing engineers to modify automation logic and add new process control loops while the AS controller remains in RUN mode. To permit delta downloads, the CPU operating system enforces strict interface signature checks (CRCs) across all function blocks.

When a block is instantiated in CFC, the compiler references the block template stored in the project's offline Blocks folder. If the block interface matches the online CPU image, changes can be downloaded seamlessly. However, if an updated or mismatched block type is introduced from an external library, the compiler flags an interface collision and disables delta downloading.

Root Cause Analysis - Elementary Blocks vs Complex APL Drivers

Engineers frequently wonder why simple blocks (such as Add04, Sub02, CmpR) can be added without compilation errors, while adding Pcs7AnIn or MotL triggers download aborts:

Elementary Blocks: Math and comparison blocks are standalone function calls (FC or elementary FB) that do not interact with hardware organization blocks or module driver diagnostic charts. Their interfaces rarely change.
APL Technology Blocks: Blocks like Pcs7AnIn and MotL are deeply integrated with the PCS 7 diagnostic architecture. During compilation with Generate module drivers, the compiler automatically instantiates diagnostic drivers (OB_DIAG1, MOD_D1, OR_M_16) in internal @-charts. If the project contains older diagnostic blocks while the new APL block demands updated driver interfaces, the compiler detects an unresolved cross-block dependency and blocks the download.

Block Type Comparison and Synchronization Matrix

The table below details block type sources, synchronization tools, and operational impact in SIMATIC PCS 7:

Block Class / ComponentLibrary SourceDependency LevelSynchronization MethodElementary Blocks (Add04, CmpR)CFC LibraryLow (Isolated)Directly usable; no module driver dependencies.APL Blocks (Pcs7AnIn, MotL)PCS 7 AP LibraryHigh (System-wide)Must synchronize via Options -> Block Types....Diagnostic Drivers (OB_DIAG1, MOD_D1)PCS 7 Basis LibraryHigh (AS Firmware linked)Auto-generated in @-charts; requires consistent versions.Master Data LibraryMultiproject RepositorySystem BaselinePrimary reference source for all project charts.CFC Update WizardOptions -> Block TypesProject AutomationSynchronizes block interfaces and updates instance DBs safely.

Step-by-Step Procedure to Update Block Types and Download Changes

Audit Master Data Library Blocks:
- In SIMATIC Manager, expand the Master Data Library -> Blocks folder.
- Verify that the target APL blocks (Pcs7AnIn, MotL) and Basic Library diagnostic blocks are present with uniform versions.
Launch Block Types Synchronization Wizard:
- Open any CFC chart in the affected AS project.
- Select Options -> Block Types....
Synchronize Master Library to AS Offline Program:
- In the Block Types dialog, select the Master Data Library in the left pane.
- In the right pane, select the target AS program.
- Select the updated blocks (or select all) and click the -> (Transfer) button.
- When prompted that existing instances will be updated, click Yes.
Perform Block Cleanup:
- Click the Clean Up button in the Block Types dialog. This removes obsolete block versions and unreferenced instance DBs.
Compile CFC with Module Drivers:
- Select Chart -> Compile -> Changes Only.
- Ensure Generate module drivers is checked.
- The compiler updates the @-charts to match the synchronized APL interfaces cleanly.
Execute Delta Download: In CFC, select PLC -> Download -> Changes Only: confirm successful download in RUN mode.

Verification

Verify block type synchronization through the following milestones:
1. Confirm that CFC compilation finishes with 0 Errors, 0 Warnings.
2. Confirm that the download changes dialog reports: 'Download changes in RUN is possible'.
3. Switch CFC to online test mode: verify that the newly added Pcs7AnIn and MotL blocks execute with valid signal status (16#80).

Limitations and Operational Precautions

Never copy individual blocks directly from external library DVDs into an AS offline block folder using drag-and-drop in SIMATIC Manager. Bypassing the Options -> Block Types... wizard fails to update instance data structures and can corrupt the CFC chart database. Furthermore, if a block update modifies inputs or outputs that alter instance DB structural sizing drastically, the compiler may declare that a full download in STOP is required. Always review the compile log before confirming online downloads on running plants.