Resolving the Siemens MP370 "Download Not Possible – OS Version Not Compatible" Error

Overview

The MP370 Multi Panel is a Windows CE based operator interface from the SIMATIC HMI family. A recurring field failure presents as a blocking transfer dialog in WinCC flexible with the exact text: "Download not possible. The 'version of the device' in your WinCC flexible project and the version of the operating system of the device are not compatible...". The error persists even after the engineer runs the OS Update routine and receives an "OS Update successful" confirmation from WinCC flexible.

The root cause is a mismatch between the panel-resident CE image version and the image version expected by the active WinCC flexible project. WinCC flexible ties the project file to a specific image major release (typically 7.x); ProTool or earlier generation installers leave a 6.x image on the panel, which WinCC flexible refuses to overwrite unless the correct image is explicitly selected. This article documents the architecture, the diagnostic steps, the correct OS update procedure, and the verification checks an automation engineer must run to recover the panel.

MP370 Hardware and Firmware Architecture

The MP370 (6AV6 644-0AA01-2AX0 family) ships with a 12.1" or 15.1" TFT, an x86 compatible CPU module, 32–64 MB working memory, a CompactFlash slot, and one or two MPI/PROFIBUS interfaces alongside Ethernet (PN/IE) and USB. The operating system is Windows CE 4.2 or CE 5.0, delivered as a CE runtime image that bundles the HMI shell, the ProSave utility interfaces, the CE registry, and the optional runtime components (S7 drivers, OPC client, etc.).

Decoding the Error Message

The full error string when translated from the dialog is:

"Download not possible. The 'version of the device' in your WinCC flexible project and the version of the operating system of the device are not compatible. Do you want to perform an OS update now?"

Three logical states trigger this dialog:

1. The panel is running a ProTool image (6.x) and the project is a WinCC flexible project (7.x).
2. The panel image is older than the image bundled with the installed WinCC flexible version (e.g., 7.0.0 on panel, 7.0.3 in the project).
3. The panel has a corrupt or partial image from a previous interrupted OS update (the panel boots to the loader, not to the runtime).

In all three cases the proper remediation is an OS Update that overwrites the panel's image with the matching WinCC flexible image file. The "Reset to factory settings" option is a red herring: it clears the project and recipe partition but does not change the image major version, so a 6.x panel will continue to refuse WinCC flexible projects even after a factory reset.

Root Cause: Why "OS Update Successful" Does Not Resolve the Error

WinCC flexible will report "OS Update successful" whenever it has finished a transfer, regardless of whether the image file selected was the correct one. The most common cause of repeated failure is a stale or wrong image file path in the OS Update dialog:

• Another Siemens tool (ProTool, STEP 7 Micro/Win, PLCSIM) has registered an old image with the OS update tool.
• The engineer browsed to an image that belongs to a different panel class (e.g., OP270 image on an MP370 panel).
• The image file was pulled from a different WinCC flexible installation on the same machine, leaving the registry pointing to the older source.

The on-panel confirmation is therefore not authoritative. The only authoritative check is the image version reported by the panel at boot (visible in the transfer/control panel menu, top right), or the version number reported in the WinCC flexible "OS Update" status window.

Prerequisites for a Clean OS Update

Before initiating the procedure, gather and verify the following:

1. WinCC flexible installation matching the project version (e.g., WinCC flexible 2008 SP5 if the project was last saved there). Reinstall the same Service Pack that originally produced the panel image.
2. The original MP370 .img file from the WinCC flexible installation media, named per the pattern MP370_*.img. Default location: C:\Program Files\Siemens\Automation\WinCC flexible\Images\<panel_name>\.
3. Ethernet crossover cable or hub-connected patch cable between the engineering PC and the MP370. Serial (RS232 MPI adapter) is supported but slower; for 32–64 MB images it is impractical.
4. Static or reserved IP address in the same subnet (e.g., PC 192.168.1.10 / panel 192.168.1.20, mask 255.255.255.0).
5. Disable Windows firewall on the engineering PC for the duration of the update, or open TCP 102 and UDP 137/138/161/162 (S7 and ProSave ports) inbound.
6. Stable 24 V supply to the MP370; do not run the OS update on a UPS that has less than 30 minutes capacity.

Step-by-Step OS Update Procedure (Correct Method)

1. Open WinCC flexible and load the project. Verify the panel type displayed in the project tree is "MP370" (12" or 15") and the version field reads the same as the project file metadata.
2. Switch the project to the matching panel in the project tree. Right-click the panel icon and select OS Update. The OS Update wizard opens.
3. Set the connection mode to Ethernet (or PROFINET). Enter the target panel's IP address. The MAC address is printed on the rating plate on the back of the unit and can also be read from the loader (no project required) via the control panel.
4. When the dialog asks to perform the OS update, click Yes. When prompted for the image file, browse manually to the WinCC flexible installation directory and select the MP370 image that matches the installation version (e.g., MP370_WinCE5_V07003001.img for WinCC flexible 2008 SP3).
5. Click through the wizard. Do not enable the "Reset to factory settings" option unless the panel is being decommissioned.
6. Click Update OS. WinCC flexible establishes a ProSave session over TCP 102, transfers the image, and reboots the panel. A 32 MB image takes 4–7 minutes over 100 Mbit Ethernet.
7. Wait for the panel to return to the loader or the runtime start screen. Do not power-cycle the panel during the auto-reboot; an interruption at this stage bricks the CE image and forces a ProTool-era recovery using the backup tool.
8. After the panel reboots, open the loader menu (right tap or the Start / Transfer / Control Panel sequence). The image version must read 7.0.x.x, not 6.x.x.x.
9. Re-initiate the project transfer from WinCC flexible. The "Download not possible" dialog should no longer appear.

Image File Selection Guide

Each WinCC flexible version ships with multiple .img files under ...\WinCC flexible\Images\<device>\. The naming convention is <panel>_WinCE<major>_V<image_version>.img. The image version must be at least equal to the version recorded in the project header. To find that version, open the project in WinCC flexible, select the panel, and read the value from the Properties dialog under Device Version.

Verification After OS Update

Once the OS update finishes, run the following checks before transferring the project:

1. Image version on panel. Loader / Control Panel / OP / Device / Image Version must show a 7.0.x.x number equal to or higher than the project version.
2. CE shell integrity. Loader menu (Transfer / Control Panel) opens without an error; the Start menu and taskbar respond; date/time can be set.
3. Interface status. Open Control Panel / Network and Dial-up Connections. The onboard Ethernet adapter must show a link. Ping from the engineering PC to the panel IP must succeed with no packet loss over a 30-second window.
4. Project transfer dry run. In WinCC flexible, choose Transfer / Transfer Settings and click Transfer. The transfer should reach the "Project compiled, transferring..." stage and write to the panel. The "Download not possible" dialog must not appear.
5. Runtime test. Once the project is on the panel, start runtime and exercise at least one tag read, one tag write, and one screen change. Any "tag error 0x0001" or "screen 0 not found" indicates a partial transfer; re-transfer the project only (no OS update needed).

Advanced Diagnostics

If the OS Update itself fails before the image is written, the engineering PC will report a ProSave error code. The most common return codes from ProSave.exe for the MP370 family are:

For deeper diagnostics, enable the ProSave trace in %ProgramData%\Siemens\Automation\ProSave\Trace.log by setting the registry key HKLM\Software\Siemens\ProSave\Trace = 1. The trace records the S7 handshake and pinpoint the failure window (typically 30–60 s after the dialog shows "Transferring OS").

Edge Cases and Field-Proven Caveats

• ProTool legacy install on the engineering PC. ProTool V6.0 SP5 registers its own OS image under ...\SIEMENS\ProTool\Images. If the OS Update wizard defaults to the ProTool path, the panel will be flashed to a 6.x image and WinCC flexible will immediately reject the next transfer. Fix: in WinCC flexible, always click Browse in the OS Update dialog and pick the path under ...\WinCC flexible\Images explicitly.
• Project saved in a newer WinCC flexible than installed. A 2008 SP5 project on a 2007 engineering station will load but the panel will only accept an image at the 7.0.2 level. Open the project in the older version, recompile, and re-transfer. The "version of the device" mismatch is a project-side property, not a runtime error.
• Memory test request. A repeated field question is whether the panel can be memory-tested like a PC. It cannot. The closest equivalent is the ProSave self-test (right-click on the panel in the project tree, Properties / Diagnostics / Self Test), which exercises the CF slot, touch, and backplane. There is no POST / BIOS screen on the MP370. The CE loader and ProSave are the only test surfaces.
• Intermittent panel start, blank screen. If the panel repeatedly fails to reach the loader after the OS update, the CF card has likely failed. Replace the CF card with a Siemens-approved Type I 128 MB–4 GB card, re-image from the original .img using an external CF reader and the boot recovery tool from the Siemens Industry Online Support portal.
• Network security software blocks ProSave. Anti-virus suites from Trend, McAfee, and Symantec have been observed to drop S7 packets on the loopback and on the LAN interface. Add ProSave.exe to the AV exclusion list and run the update with the AV real-time scanner paused.

When the Panel Is Truly Bricked

If the panel powers up but shows only a black screen and the loader menu cannot be reached, the image is corrupted. Recovery steps:

1. Power the panel down for 30 s, power back up. If the loader appears, run the OS Update as documented above.
2. If the loader does not appear, the panel can be forced into the recovery loader by holding the right side of the touch during power-up. The recovery loader offers a single "Restore image from CF" option. Place the recovery .img on a CF card inserted in the panel's slot, select the option, and wait. The panel will write the image and reboot to the loader.
3. If neither procedure succeeds, the panel requires depot repair. Contact Siemens Customer Support with the panel's serial number, MLFB (e.g., 6AV6 644-0AB01-2AX0), and the failure log from the engineering PC.

Recommended Reference Documentation

For the full reference on WinCC flexible image management, the engineer should consult the WinCC flexible Engineering documentation set on the Siemens Industry Online Support portal. The OS Update chapter details the file format, transfer protocol, and the conditions under which a project is considered compatible with a given image. The MP370 device manual provides the panel-specific pinouts, the loader entry sequence, and the CF card replacement procedure.

FAQ