Resolving 'OB Block Is Not Copied' and Download Locks on CPU 410 SMART in PCS 7 V8.2

In SIMATIC PCS 7 V8.2, the download failure 'OB block is not copied' (often accompanied by 'Error 294:6 - The block OBx is open in another application') occurs when Organization Blocks (e.g. OB1, OB35, OB100) or CFC charts are open in an active editor window during download, locking the blocks in engineering memory. On specialized controllers like the CPU 410 SMART, strict block consistency checks immediately abort the download. To resolve this, close all open LAD/FBD/STL editors, exit CFC test mode, ensure the CPU operating state permits download, and retry the download.

STEP 7 Block Locking Architecture During Download Operations

In SIMATIC PCS 7, downloading hardware configuration or program logic to an S7-400 or CPU 410 controller requires coordinated memory management:
* When an engineer opens an Organization Block (OB1, OB35, OB82) in the classic LAD/FBD/STL Editor, STEP 7 places an exclusive file lock on that block's database record in the engineering station's memory.
* When a CFC chart is opened in Test Mode (Online Monitor Mode), the CFC environment maintains persistent communication handles linking offline block instances to the online CPU execution memory.

During a download sequence (whether 'Download in RUN' or 'Entire Program in STOP'), the STEP 7 download engine (s7tgtopx.exe) must compile, transfer, and atomically swap machine code blocks in the controller's load memory. If any internal component or Organization Block is currently locked by an open editor window, the download engine cannot overwrite the block, aborting the transfer with:
Error 294:6: The block OBx is open in another application and cannot be copied.

Specific Constraints of the SIMATIC CPU 410 SMART Controller

The SIMATIC PCS 7 CPU 410 SMART is a specialized process controller tailored for compact skid applications:
* Architecture: Derived from the high-end CPU 410-5H hardware platform, but restricted via firmware and its System Expansion Card (SEC) to specific maximum Process Object (PO) tiers (typically 800 POs).
* Firmware Validation: The CPU 410 SMART enforces rigorous block consistency and licensing validation during download. Any mismatch between the configured hardware order number, SEC PO capacity, or uncompiled Organization Blocks triggers an immediate download rejection.
* If an engineer attempts to download standard unassigned blocks or leaves dummy OBs open while downloading hardware configuration, the CPU 410 SMART halts the transfer to prevent inconsistent memory allocation.

Root Causes for 'Error 294:6 Block Is Open in Another Application'

Three primary conditions trigger this download lock:
1. Open Block in LAD/FBD/STL:
An engineer opened OB1 or OB35 from the S7 Program block folder to inspect execution cycle logic, leaving the editor window minimized on the Windows taskbar.
2. Lingering Background S7 Processes:
If an earlier STEP 7 or CFC session crashed or was terminated abruptly, background processes such as s7wndx.exe (LAD/STL editor engine) or s7xudiax.exe continue holding database file locks in memory.
3. CFC Test Mode Active:
One or more CFC charts have dynamic monitoring enabled (yellow sunglasses active), locking the execution sequence table.

Controller Download State and Lock Diagnostics Matrix

The following matrix compares download failure symptoms and their diagnostic resolutions:

Error Code / SymptomUnderlying CauseImmediate Action RequiredError 294:6 (OB is open)Editor window has block open in RAMClose LAD/STL editor window; retry downloadError 294:6 (No visible windows)Orphaned background s7wndx.exeEnd task via Windows Task ManagerError: Block cannot be copied in RUNBlock interface changed or CiR limitPerform Changes-only download, or STOP ASCPU 410 PO Limit ExceededProgram exceeds SEC capacityReduce PO count or upgrade SEC expansion cardTarget memory full (Load Memory)Fragmented CPU RAM / FlashPerform CPU memory compression (MRES)

Step-by-Step Procedure to Clear Download Locks and Complete Download

Follow this procedure to eliminate download locks on CPU 410 SMART:
1. Close All Open Editors:
- Save and close all open LAD, FBD, and STL editor windows.
- Close all open Variable Tables (VAT).
- In all open CFC charts, click the Test Mode icon to turn off online monitoring. Close the CFC editor completely.
2. Verify Process Cleanup in Task Manager:
- Press Ctrl + Shift + Esc to open Windows Task Manager.
- Check the Details / Processes tab:
- If s7wndx.exe (LAD/FBD/STL Editor) is running without an open window, terminate the process.
- Ensure s7tgtopx.exe (SIMATIC Manager) is stable and not unresponsive.
3. Save and Compile HW Config and CFC:
- In SIMATIC Manager, open HW Config. Click Save and Compile. Close HW Config.
- Open CFC: Execute Compile -> Charts as Program -> Scope: Changes only. Confirm compile finishes with 0 Errors.
4. Execute Download:
- In SIMATIC Manager, select the target S7 Station or CPU 410 SMART.
- Select PLC -> Download.
- In the target dialog, select the target CPU and click OK.
- Confirm that all blocks (including OBs, FCs, and DBs) transfer smoothly without reporting Error 294:6.

Verification

Verify that download completes cleanly and controller executes:
1. Observe the STEP 7 download progress bar: Confirm all blocks transfer without interruption.
2. In SIMATIC Manager, open the CPU Diagnostic Buffer (Ctrl + D):
- Confirm the latest entry reads: RUN mode entered or Download of blocks completed.
- Confirm zero entries for block copy errors or memory allocation faults.
3. Open a CFC chart: Enable Test Mode (Online Monitor). Verify that block inputs and outputs update with live process values.
4. Verify that CPU 410 SMART front-panel LEDs display solid green RUN and dark SF / BF indicators.

Limitations and Operational Precautions

Terminating STEP 7 processes forcefully via Task Manager while a database write is occurring can corrupt the .s7p project database; always close editors gracefully whenever possible.
On active production facilities, never switch the CPU to STOP mode to force a download without written authorization from plant operations.
Hardware licensing note: CPU 410 SMART controllers have strict PO license limits hard-coded into their System Expansion Cards; verify PO counts before compiling extensive projects.

Engineer FAQ

Why did the user see OB1 in a PCS 7 project?

In standard PCS 7, engineers should never manually create or edit OB1 in LAD/STL. The CFC compiler automatically manages Organization Blocks. Opening OB1 manually frequently introduces illegal code that clashes with CFC task scheduling.

Can CPU 410 SMART be upgraded to a standard CPU 410-5H?

No. The CPU 410 SMART is hardware-locked to specific regional markets and smaller PO tiers. Full-scale plant expansions require standard CPU 410-5H hardware.

What does Error 33:1707 mean during download?

Error 33:1707 indicates that the online CPU does not have sufficient contiguous load memory to accommodate the new compiled block. Compressing the CPU memory or deleting obsolete blocks resolves this error.