Resolving Siemens MP277 10 Key HMI Stuck on Starting Windows CE

1. Problem Description

The SIMATIC MP277 10" Key panel halts during boot with both the splash logo and the boot-loader status string visible at the same time:

• Splash line (LED-back-lit background): Starting Windows CE - Please Wait ...
• Lower status line (boot-loader diagnostics): Firmware Init Done

The progress marquee of dots stops expanding anywhere between 5 % and 99 % of the bar; the touch screen is inactive, the function keys have no effect, and the configured WinCC flexible project is never displayed. The unit is bricked at the firmware / operating-system layer while the electronics themselves remain functional.

2. Affected Hardware, Firmware, and Engineering Software

The OS image and recovery flow are identical for the 8" Touch (6AV6 643-0CB01-0AX1), 10" Touch (6AV6 643-0CD01-0AX1) and 10" Key variants; only the calibration and the screen geometry differ at commissioning.

Engineering tools that can generate the matching OS image and trigger the update:

• SIMATIC ProTool V6.0 SP3 (legacy image, still used by older stock)
• SIMATIC WinCC flexible 2008 SP3 or later (most common in the field; supports Transfer → OS Update)
• SIMATIC TIA Portal V13 SP1 or later with the option WinCC (TIA Portal) Maintenance
• Stand-alone ProSave V9.x (bundled with the WinCC flexible DVD under \Support\ProSave)

All of these rely on the image files distributed under <install>\Siemens\WinCC flexible\Images\MP277 and named MP277_Keys_Vx.x.x.x.img. Each release is identified by the four-segment version reported by Control Panel → System after the update.

3. Boot Stages and Diagnostic State Machine

The MP277 passes through four boot milestones. Understanding the time stamps helps to localise where the failure occurred:

If the panel is still on stage 2 after 60 s, the kernel has not reached stage 3: the boot is hung inside the firmware / registry phase and an external OS update is required. The Siemens support entry "How do you perform an 'Operating system update' (OS update) or 'Reset to factory settings' on operator panels?" describes the recovery flow used here and applies to every MP, KTP and Comfort panel running Windows CE.

Use the diagram below to choose the correct recovery path based on the still-visible text:

4. Root Cause Analysis

Symptom-locked root causes that produce exactly the "Firmware Init Done + frozen splash" state:

1. Registry hive corruption — an abrupt 24 V drop while the runtime was writing tag values or option data writes garbage into the file \Mounted Volumes\Hive\default.reg; the kernel panics during the StartConfig phase.
2. Aborted firmware / OS update — the panel was power-cycled, the CF card removed, or the serial/Ethernet link unplugged while ProSave was writing the OS image, leaving a partial NK.bin and a corrupt initns.dat set.
3. Defective CompactFlash transfer card — when the project boots from an external CF card, bad blocks make the boot-loader report Firmware Init Done but prevent the second-stage mount of the registry hive.
4. Internal battery fully discharged — the buffered SRAM that holds alarm logs and recipes rolls back to defaults, which can trigger a registry repair that never finishes.
5. User-initiated wipe — an operator ran the Reset or Clear action from the Control Panel and removed 24 V before the wipe of \Windows\StartUp completed.
6. Project software compatibility mismatch — pairing a ProTool V6.0 image with a WinCC flexible 2008 SP4 project (or vice-versa) corrupts the user partition during the second start-up.

5. Prerequisites, Cables, and Update-Mode Activation

Prerequisites

• Engineering PC with Windows 7, Windows 10 or Windows 11 (32- or 64-bit) and at least 1.0 GB free disk space.
• One of the engineering tools listed in section 2.
• Siemens ProSave (included in WinCC flexible and TIA Portal). A stand-alone installer ships on the WinCC flexible DVD at \Support\ProSave\Setup.exe.
• Appropriate connection cable (see cable table below).
• Matching OS image file MP277_Keys_Vxxx.img.
• Backup of the panel project (compiled .fwx or, ideally, the entire WinCC flexible source archive *.log + *.fwd).
• Free USB slot or MPI port on the engineering PC; the panel-side function keys F1, F4 and ESC must be reachable while applying panel power.

Cable and Interface Selection

Ethernet is the preferred path because it survives a corrupt registry: the boot-loader exposes a TFTP server on UDP port 69 even when Windows CE itself does not start. The MPI / PROFIBUS path is the legacy fallback used by ProTool V6.0.

The serial null-modem cable (6AV6 671-1CB00-0AX2) is sometimes referenced as the "RS-232 / TTY cable"; only this cable, or an equivalent pinout (2-3 crossover, 4-5 loopback, 6-20 tied), will bring up the loader menu.

Forcing the Panel into Update Mode

The MP277 boot loader must accept the keystroke before Windows CE attempts to mount the file system. Execute the following sequence without deviation:

1. Switch off the 24 V supply to the panel.
2. Press and hold F1 on the bottom-left function-key cluster.
3. Re-apply 24 V DC.
4. Keep F1 pressed until the LCD reports the boot-loader banner Boot Loader Vx.x.x and the menu [1] Download OS Image [2] Boot from CF [3] Reset [4] Exit (approximately 6 s).
5. Release F1 and select [1] with the arrow keys; press F4 (Enter).

If the keys do not register (possibly because the keypad firmware itself is corrupt), cycle power three times with 5 s intervals; the boot-loader enters the recovery menu automatically after the third reset.

6. Method 1 — OS Update with ProTool (Legacy)

This remains the correct path for installed bases where engineering still uses ProTool V6.0 and the OEM image set SIMATIC_PT_MP277_OSP2.iso.

1. Connect the panel with the PPI adapter (MLFB 6ES7 901-3CB30-0XA0) directly to the PC.
2. Open ProTool and launch Options → Transfer → OS Update.
3. Select the PPI interface and station address 1.
4. Browse to the image file MP277_Keys_Vxxx.img matching the panel MLFB.
5. Tick "Reset to factory settings after update" — the loader reformats the user partition and re-creates the default registry.
6. Click Start. ProTool erases the flash and writes the new image in approximately 6 minutes.
7. The panel restarts automatically. After about 30 s the screen shows Loading Project …, the cue that the WinCC flexible runtime is launching.

Connection details and prerequisites:

• Engineering PC running Windows XP SP3, Windows 7 (32-bit) or Windows 10 (64-bit) with the legacy ProTool USB driver installed in compatibility mode.
• ProTool V6.0 SP3 must be authorised with the original licence key on the parallel port or a USB licence dongle.
• The PPI adapter plugs into the panel's X1 PROFIBUS socket (rear-side 9-pin D-sub).

7. Method 2 — OS Update with WinCC flexible

This is the path recommended by Siemens support for installed bases using WinCC flexible 2008 SP3 / SP4 or a project migrated into TIA Portal.

1. Open WinCC flexible 2008, load the project, then launch Transfer → OS Update (Ctrl + Shift + U).
2. Choose the connection: MPI/PROFIBUS, Ethernet, USB or Serial. Use the same address as the project itself (default 1 for MPI, IP from the engineering project for Ethernet).
3. From the drop-down Image version, select the OS image that ships with WinCC flexible — located at <install>\Siemens\WinCC flexible\Images\MP277.
4. Check "Reset to factory settings" (recommended after a boot hang).
5. Click "Update OS". ProSave opens. Confirm the prompt "Reset and update".
6. Wait for ProSave to report Update successful. The panel restarts with a clean Windows CE shell. No project is loaded.

ProSave channel settings reference

8. Method 3 — Reset to Factory Settings via TIA Portal

Use this path when the engineering environment is already migrated to TIA Portal V13 SP1 or later and the panel is part of a TIA device tree.

1. Open TIA Portal. Add the MP277 as a device in the project tree.
2. Navigate to Project → HMI → Maintenance → OS Update.
3. Pick the panel type MP 277 10" Key, select Ethernet (recommended) or USB / PROFIBUS.
4. Tick "Format user data" to wipe recipes, alarm history and language tables that survived the bad shutdown.
5. Click "Go Online and Run" and accept the prompt "Operating system will be reset to factory settings".
6. After completion the panel reboots into the WinCC-CE Control Panel; the operator is prompted to set language, region and IP address.
7. Re-create the device certificate (TIA panel certificates are stored on the user partition and are lost when the partition is formatted).

TIA Portal reads the matching panel image from the WinCC (TIA Portal) DVD / HSP. Confirm that the HSP version is ≥ V13.0 if the panel is firmware V13.0 or newer; mismatches are flagged in the diagnostics buffer before the transfer starts.

9. Alternative: OS Update via External CF Card

Used when the engineering PC cannot reach the panel across Ethernet or PROFIBUS — for example a machine that has been moved to a commissioning area without network infrastructure.

1. Insert a 256 MB to 2 GB CompactFlash card into the PC.
2. Format the card as FAT16 with default cluster size.
3. Copy the OS image MP277_Keys_Vxxx.img to the root of the card, and rename it to IMG.MP277.
4. Power down the panel. Slide the CF card into the slot on the rear of the unit.
5. Hold the CF/PG button on the side of the panel while applying 24 V DC.
6. The panel prompts "CF image found, press F4 to install". Press F4; the loader flashes the OS in roughly 4 minutes.
7. When the panel restarts, withdraw the CF card and proceed to the project transfer (section 11).

10. Verification and Health Checks

11. Post-Recovery Transfer, Commissioning, Watchpoints, and Glossary

11.1 Project Transfer

Because the OS update wipes the project partition, load the original WinCC flexible project back to the panel:

1. Open the compiled project in WinCC flexible (or TIA Portal in WinCC flexible project mode).
2. Select Transfer → Transfer (Ctrl + Shift + T).
3. Use the same channel as the OS update (Ethernet / MPI / USB).
4. Select "Overwrite all"; this replaces templates, tag tables and the recipe DB.
5. Click "Transfer"; the panel briefly shows "Stopping Runtime", then "Starting Runtime", and finally the project home screen.

For a fully unattended rollout, copy the compiled file *.fwx to a CF card under \SIMATIC\HMIPNL\, slide the card in, and power up. The MP277 automatically copies the file and restarts the runtime.

11.2 Field Commissioning Checklist

1. Before applying 24 V, visually inspect the 24 V clamp for reverse-polarity burns or loose torque (recommended 0.5 – 0.6 Nm).
2. Verify the chassis ground is bonded to cabinet PE within 100 mm of the panel stud.
3. Configure the boot mode CF Boot Priority = Off unless the panel is being permanently run from a CF card.
4. Issue the OS update, then immediately load the project, then run the "Stop Runtime" / "Start Runtime" cycle once to verify the HmiHost.exe instance regenerates cleanly.
5. Record the Control Panel → System → Serial number into the asset register.
6. Archive the image version + the .fwx checksum in the project's documentation set.
7. Set the panel timezone and the daylight-saving rules to match the controller (PLC Date/Time or S7 Date/Time).

11.3 Prevention and Watchpoints

• Power the panel through a UPS or DC battery module; avoid cutting 24 V during runtime writes or while in Control Panel → Clear/Reset.
• Always select "Reset to factory settings" when updating the OS, even on healthy panels — it prevents incremental registry corruption that compounds over months of operation.
• Periodically export the project with "Complete restore" to a secure PC. Use WinCC flexible option Project → Backup / Restore every 6 months.
• Replace the internal lithium backup battery (type CR2450 / 3 V, holder on the back of the unit) every 8 years. A discharged battery combined with a power cycle triggers the boot hang on roughly 5 % of field units.
• Inspect the CF transfer card with chkdsk /r; bad blocks on the card surface mimic OS corruption on the panel.
• Always upgrade through the same major firmware family. Mixing a ProTool V6.0 image with a WinCC flexible 2008 SP4 image occasionally bricks the user partition permanently.
• Disable QuickBoot on panels inside machines that may be warm-cycled more than 5 times a day; quick-boot reuses stale registry records by design.

11.4 Glossary

Refer to the Siemens Industry Online Support portal at support.industry.siemens.com for the latest firmware hotfixes and HSPs; the canonical FAQ for OS update and reset-to-factory is accessible at support.industry.siemens.com/cs/ww/en/view/21838668.

12. Frequently Asked Questions