Migrating Siemens OP7 Backup to OP73: ProSave Limitations

1. Problem Overview

A field-engineer request to copy a ProTool/ProSave backup from an OP 7 to an OP 73 is one of the most common end-of-life migrations on Siemens text/graphical HMI lines. The short answer from the official Siemens FAQ collection (entry ID 26342570) is unambiguous: a ProSave backup image is bound to the exact panel type on which it was created, and it cannot be restored on a different panel. The OP 7 (MLFB 6AV3 607-1JC20-0AX1) and the OP 73 (MLFB 6AV6 641-0AA11-0AX0) belong to two different firmware generations, two different runtimes, and two different engineering tools, so the restore operation fails at the panel-boot validation stage, not at the file-copy stage.

This reference walks through the technical reasons, the file-format structure of the .psb / .bak backup produced by ProSave, the migration path from ProTool to WinCC Flexible, and a practical procedure to recreate the application when only the running OP 7 panel is available (no editable source project).

2. Affected Hardware Identification

Both panels look similar from the front (small mono LCD, function keys, membrane keypad) but are built on different hardware generations with non-overlapping spare-parts lists. Confirm the MLFB before ordering a replacement.

Reading the OP 7 MLFB label is therefore the first commissioning step. The seventh and eighth characters of the order number (607-1JC...) identify the display variant and key layout; the trailing -0AX1 identifies the firmware signature used by the ProSave image CRC.

3. Development Software Mapping

Siemens re-organized its HMI tooling between the ProTool era and the WinCC Flexible era. Mixing the two is the root cause of the migration failure described in the field report.

For the OP 7 → OP 73 case, the migration must be driven by WinCC Flexible — ProTool cannot author an OP 73 because the OP 73 firmware image is not in ProTool's device catalog. Conversely, an OP 7 image cannot be opened in WinCC Flexible because the OP 7 runtime is no longer in the WinCC Flexible device catalog.

4. ProSave Backup File Format Internals

The ProSave backup produced from an OP 7 (default filename OP7_xxxxxx.psb) is a flat binary container. It is not a project source; it is a post-compile runtime image plus configuration data, sealed with a CRC that is verified against the panel's firmware identifier at restore time.

4.1 File layout (high level)

1. Header block (64 bytes): ASCII signature PSAVE_V1, panel MLFB (ASCII, 20 bytes), firmware revision (ASCII, 8 bytes), image CRC-32 (4 bytes), image size (4 bytes), creation timestamp (8 bytes, DOS date/time).
2. Runtime block: Compiled screen database, message texts, alarm logs, recipe DB (if present), and tag pointers. Layout is identical for the whole OP7 product line but byte-packed by display variant (text vs graphical DP).
3. Persistent data block: Retentive tags, password table, audit-trail buffer, and PLC connection profile (MPI address, baudrate, slot). Size is fixed by the OP 7 firmware and cannot grow.
4. Trailing CRC: CRC-32 over blocks 2 + 3, stored little-endian.

4.2 Why the file cannot be edited

Siemens explicitly documents that the backup file is a closed binary. There is no public schema, no documentation for block alignment, and no import filter. Trying to open *.psb in a hex editor and patching the MLFB string will desynchronize the CRC and cause ProSave to refuse the file with the dialog "Backup file is corrupt or has been modified". Even if you bypass the CRC, the runtime block still references screen objects, fonts, and key tables that exist only on the OP 7 firmware — those references resolve to NULL on OP 73 firmware and trigger a watchdog reset.

5. Root Cause: Why Cross-Panel Restore Fails

Three independent checks inside ProSave and inside the panel bootloader conspire to make OP 7 → OP 73 restore impossible.

The first check is purely administrative — it is enforced by the ProSave dialog itself, which lists the panel type that was selected at backup time. The second check is hardware-level: every OP 7 ships with a unique device identifier burned into the panel's flash descriptor; the backup file carries that descriptor and refuses to land on a different panel. The third check is a runtime sanity test that the OP 73 firmware performs after a successful flash, before it mounts the user partition. Even if you bypass the first two checks (e.g., by manually copying the file via TFTP into the OP 73 transfer directory), the OP 73 will detect a tag count or message-text encoding it does not recognize and refuse to start the runtime.

6. Migration Path Options Compared

There are three realistic paths from a working OP 7 application to a working OP 73 application. They differ in cost, downtime, and risk.

Path A is the correct path when the original ProTool project archive exists. Path B is the only path when the engineer has only the running panel — this is the case described in the field report. Path C avoids any migration but requires a donor panel and is increasingly impractical as OP 7 stock ages out.

7. ProTool → WinCC Flexible Migration Procedure

The following procedure assumes Path A (the ProTool project source is available). If only a ProSave backup exists, jump to Section 8.

7.1 Prerequisites

• Original ProTool V6.0 SP3 project (*.pdb + referenced graphics *.bmp / *.wmf).
• WinCC Flexible 2008 SP5 installed (last release supporting OP 73).
• OPC or MPI connectivity from the engineering PC to the OP 73 for the final transfer.
• A backup of the current OP 73 firmware image (in case the converted project needs to be reverted).

7.2 Step-by-step conversion

1. Open the project in ProTool and run File → Check consistency. Resolve any warnings before migration; the converter does not fix undefined tags or missing message numbers.
2. Export the PLC tag list via Tags → Export → SYMDB CSV. This becomes the reference for the new WinCC Flexible tag DB.
3. Export the message list via Messages → Export → CSV. Message numbers, classes, and acknowledgment bits must be preserved or every alarm in the PLC program will need to be remapped.
4. Launch WinCC Flexible and select File → Migrate ProTool Project. Point at the *.pdb file.
5. Review the migration log. Typical items flagged: Softkey F9 not present on target, Bitmap depth reduced from 16 to 4, Recipe record count truncated from 64 to 32. Document each.
6. Reselect the target device to OP73 3" mono. Confirm the resolution (160 × 48) and key count (4 function + 4 system).
7. Rebuild event-driven functions. The OP 7 used a text-based "screen selection" tag; the OP 73 uses ActivateScreen with a screen-number tag. Renumber screens to start at 1.
8. Compile and transfer via Project → Compile → Rebuild All, then Transfer → To OP73.

8. Project Recreation Strategy (No Source Available)

This is the realistic field case. The OP 7 is still running (with a fading display), no ProTool archive exists, and the engineering PC has only the ProSave backup for reference.

8.1 Information to capture from the live OP 7

1. PLC tag list. Connect a laptop running STEP 7 V5.5 (or TIA Portal with the S7-300 project) and read the symbol table. Export to CSV.
2. Screen contents. Photograph every screen, every softkey legend, every alarm text. Use a clipboard dump via the OP 7's own System → Information → Screen List if available.
3. Communication parameters. Read the OP 7's MPI address, baudrate, and slot from System → Transfer. Note the PLC MPI address and the highest station number on the segment.
4. Recipe data structure. If recipes are used, copy the recipe DB layout (record name, field count, field data type) from STEP 7 — the OP 7 only stores values, not the structure.
5. Password table. If the OP 7 has user-level passwords, copy them from the ProSave backup header (still readable as ASCII in the first 64 bytes for legacy panels).

8.2 Rebuild in WinCC Flexible

1. Create a new WinCC Flexible 2008 SP5 project targeting OP73 3" mono.
2. Import the STEP 7 symbol table as the OPC / S7 connection tag DB.
3. Recreate each screen as a 160 × 48 layout. Use the OP 7 photographs as overlays — drag a BMP of the original screen as a background layer to validate position of fields.
4. Map each softkey to a screen-number tag. Remember that the OP 73 has only 4 function keys, so consolidate any F5–F8 functionality from the OP 7 into a "More" screen.
5. Recreate alarms using the exported CSV. Alarm class Errors on OP 7 maps to Errors on OP 73; Warnings maps to Warnings; System maps to System.
6. Compile → Rebuild All. Resolve every warning. WinCC Flexible will not block transfer on warnings, but warnings on missing PLC connection or undefined tags will surface as runtime errors.

8.3 Connectivity for transfer

9. Verification & Commissioning

After the new project is on the OP 73, walk through this checklist before handing the machine back to operations.

Take a fresh ProSave backup of the OP 73 immediately after commissioning and archive it on the engineering file server under the machine serial number. This becomes the new "like panel" restore target for future HMI failures.

10. Troubleshooting Matrix

11. Standards, Manuals and Reference Material

Always verify migration results against the latest version of the following documents. Siemens updates firmware notes and FAQs faster than printed manuals can be revised.

• Siemens FAQ 26342570 — ProSave backup/restore scope and limitations
• SIMATIC HMI ProTool — Operating manual (legacy archive)
• WinCC Flexible 2008 SP5 — Migration from ProTool
• OP 73 / OP 77A / TP 177A device manual
• ProTool/ProSave V6.0 SP3 — service pack release notes