Problem Overview: SP3 Engineering Station Cannot Download to SP2 Runtime
A common field failure on brownfield SIMATIC HMI installations occurs when a maintenance engineer upgrades the WinCC Flexible 2008 Engineering Station (ES) on a programming laptop to Service Pack 3 (SP3) while the HMI PC Runtime (RT) on the production line still runs SP2. The Transfer dialog either shows an empty project list or refuses to compile a build targeted at the older Runtime. Production cannot be stopped for an hour to update the live HMI PC, yet the engineer must deploy a small change to a running line.
This article documents the underlying compatibility model between WinCC Flexible 2008 ES and RT service packs, the precise error conditions that block the transfer, and four field-proven resolution paths ranked by lowest to highest operational impact.
WinCC Flexible 2008 SP Compatibility Model
WinCC Flexible 2008 uses a forward-compatible / non-backward-compatible build model. The Engineering System produces a compiled *.fwx project image (or *.pdz for older panels) that embeds a version tag matching the highest Runtime the project is targeted against. The Runtime validates this version tag on every transfer and on every cold start of the HMI.
| ES Service Pack | Build Number (approx.) | Can compile for RT version | Can transfer to RT version |
|---|---|---|---|
| SP1 | V1.3.x | RT 2008 SP1 only | RT 2008 SP1 only |
| SP2 | V1.4.x | RT 2008 SP1, SP2 | RT 2008 SP1, SP2 |
| SP3 | V1.5.x | RT 2008 SP1, SP2, SP3 | RT 2008 SP1, SP2, SP3 |
| SP4 | V1.6.x | RT 2008 SP1–SP4 | RT 2008 SP1–SP4 |
| SP5 | V1.7.x | RT 2008 SP1–SP5 | RT 2008 SP1–SP5 |
Critical rule: the ES service pack must be equal to or higher than the highest RT service pack in the system. A lower SP ES can open a higher SP project only if it was originally saved in a compatible mode; a higher SP ES cannot compile down to a lower SP RT.
Root Cause: Why SP3 ES Rejects an SP2 RT
When the engineer opens the project on the SP3 laptop, edits it, and tries to download, three checks fire sequentially:
- ES-RT version check (compile time): The compiler refuses to produce a build for an RT version older than itself. The error reads: "The selected Runtime version is older than the Engineering System. Compilation is not possible."
-
Transfer version check (transfer time): Even if the engineer manually edits the device version to "WinCC Flexible 2008 SP2 RT" in the Device Settings, the transfer utility detects that no
*.fwxfile exists for that target. The download list is empty. - Reverse-compile check (open time): The ES will not load a project previously compiled under SP3 if it is opened on SP2 because the internal project container version is higher.
Solution 1: Save As Older Project Version (Lowest Impact)
The Save As Project Version function downgrades the source project file on disk so it can be opened by an older ES, but it does not rebuild the Runtime image. Used alone this is insufficient for direct transfer, but combined with Solution 2 (a second laptop or VM holding the SP2 ES) it becomes the standard field procedure.
- On the SP3 ES, open the project.
- Menu: Project → Save As → Save As Older Version.
- Select WinCC Flexible 2008 SP2 as the target version.
- Click Save. A new
*.hmifile is written. - Copy the file to the SP2 ES, recompile, and transfer.
Solution 2: Virtual Machine with Matched SP ES (Most Common in Field)
For engineers managing multiple plants on different SP baselines, the standard approach is to maintain one virtual machine per required service pack on the same laptop. The host laptop runs the newest SP; a VMware Workstation / Hyper-V / VirtualBox VM holds the older SP for legacy plant support.
- Install the matching SP2 ES inside a Windows XP or Windows 7 32-bit VM. WinCC Flexible 2008 SP2 is 32-bit only; do not attempt 64-bit native install.
- Allocate a dedicated bridged network adapter to the VM so it can reach the HMI PC subnet.
- Share the project folder over the VM host network or copy the project file in via the VM tools.
- Open the project, recompile against the SP2 RT, and transfer.
| VM Parameter | Recommended Value | Reason |
|---|---|---|
| OS | Windows 7 SP1 32-bit | Last supported by WinCC Flexible 2008 SP2 |
| RAM | 2 GB minimum, 4 GB recommended | ES is RAM-hungry with large projects |
| Network | Bridged adapter, fixed IP | Required for Ethernet transfer to HMI PC |
| Disk | 40 GB dynamic | ES + SP + project archives + delta copies |
| USB passthrough | Enabled | Required for MPI/Profibus adapter transfer |
Solution 3: Update the Live HMI PC Runtime (Highest Impact, Cleanest State)
If the production line allows a one-hour outage, the cleanest resolution is to bring the HMI PC Runtime forward to the same SP as the ES. The procedure:
- Schedule the production stop with operations. Confirm backup power for the HMI PC (UPS) and the PLC S7 connection remains live.
- Copy the SP3 Runtime installer (
WinCC_Flexible_2008_Runtime_SP3.exe) to the HMI PC or to a network share reachable by the HMI PC. - Stop the WinCC Flexible Runtime service:
net stop "WinCC flexible 2008 Runtime"from an elevated command prompt. - Run the SP3 Runtime installer. It will detect the existing SP2 install and upgrade in place. Do not uninstall first; the registry and project paths must be preserved.
- Reboot the HMI PC. Verify the RT version in the system tray Runtime control panel: Start → SIMATIC → WinCC flexible 2008 Runtime → About. It should read Version 1.5.x.x for SP3.
- From the SP3 ES, perform the transfer. The empty-project bug is gone because the RT version now matches the ES version.
Project.hmi running image survive the in-place upgrade. Always back up C:\Program Files\Siemens\Automation\WinCC flexible 2008 Runtime\HmiRtm\ to a safe location before starting.Solution 4: Dual-Boot or Second Laptop with SP2 ES
For sites that forbid VMs on control-system laptops (common in validated / GxP environments), the alternative is a second physical machine pre-imaged with WinCC Flexible 2008 SP2 and its required license key (Floating License or Single License on USB dongle). The procedure mirrors Solution 2 but uses real hardware. Keep both machines patched independently; the SP2 machine should be air-gapped from the production network except during transfer windows.
Step-by-Step: Recommended Field Procedure
The following end-to-end procedure assumes Solution 3 (Runtime upgrade) is approved. It is the only procedure that puts the system into a single, consistent SP level and removes the future recurrence of the same problem.
- Pre-checks. From the SP3 ES, open the project and run Project → Compiler → Check Consistency. Resolve every warning.
-
Backup the live HMI project. On the HMI PC, use the ProSave tool (Start → SIMATIC → ProSave) to back up the running project to a USB stick or network share. ProSave creates a full
*.psbbackup that can be restored if the upgrade fails. - Verify the SP level of the HMI PC. Open WinCC flexible 2008 Runtime control panel on the HMI PC. The splash screen and About dialog show the exact service pack. Record it.
- Stage the SP3 Runtime installer. Copy it to the HMI PC local disk; do not run it from a network share. Verify the file checksum against the Siemens download entry.
-
Stop the Runtime service. Use the system tray icon or
sc stop "WinCC flexible 2008 Runtime"from an admin command prompt. - Run the SP3 Runtime installer. Accept the in-place upgrade. Do not change the installation directory.
- Reboot the HMI PC. Confirm the new version in the About dialog after reboot.
- Transfer the project. On the SP3 ES, open the project, choose Project → Transfer → Transfer. Set the transfer mode (Ethernet / MPI / Profibus / USB / Profinet) to match the physical connection. Click Transfer.
- Verification. The Runtime restarts automatically with the new project. Confirm the modified screens, scripts, and tags load and respond. Check the Runtime event log for warnings.
Transfer Mode Reference
| Mode | Typical Cable | Default Port on HMI PC | Notes |
|---|---|---|---|
| Ethernet (TCP/IP) | Standard Cat5e/Cat6 crossover or patch | UDP 6000, TCP 102 | Fastest; supports delta transfer |
| Profibus / MPI | Siemens PC Adapter USB A2 (6GK1571-0BA00-0AA0) | COM port mapped to adapter | Legacy plants only; slow |
| Profinet | Standard Ethernet | UDP 34964 | Used when HMI is on Profinet with S7-300/400 |
| USB | USB A to Panel USB | N/A | PC-based Runtime only; not for transfer to panel |
| Serial (RS-232) | Null-modem cable | COM1 | Very old panels only |
Configuring Reverse Transfer (SP3 ES → SP2 RT) When Downgrade Is Mandatory
If the live Runtime absolutely cannot be updated and a VM is not available, the engineer can attempt a manual reverse compile workaround. This procedure is unsupported by Siemens and is documented for field completeness only.
- On the SP3 ES, perform Save As Older Version → WinCC Flexible 2008 SP2.
- On a separate machine, install WinCC Flexible 2008 SP2 ES with a compatible license.
- Copy the saved SP2
*.hmiproject to the SP2 machine. - On the SP2 ES, open the project, Device Settings → Device → select the SP2 Runtime target.
- Compile: Project → Compiler → Build. This produces a fresh
*.fwximage tagged for SP2 RT. - Transfer to the HMI PC. The transfer will succeed because the version tags match.
Known Issues and Field-Caught Edge Cases
| Symptom | Root Cause | Workaround |
|---|---|---|
| Transfer dialog shows empty project list | RT version on HMI PC older than ES | Apply Solution 3 (Runtime upgrade) or Solution 1+2 (Save As + VM) |
| Compile error: "Object type not supported in target version" | SP3-only object used in project | Replace with SP2-compatible equivalent; check WinCC Flexible SP3 release notes for new object types |
| Runtime crashes after transfer; event log shows "Image CRC mismatch" | In-place SP upgrade left a stale *.fwx cache |
Delete Project.hmi.cmp and *.log in the Runtime project folder; restart service |
| Transfer hangs at 99% | Firewall on HMI PC blocks UDP 6000 | Add firewall rule: allow inbound UDP 6000 and TCP 102 for subnet |
| Cannot find SP2 installer on Siemens support portal | SP2 superseded; older downloads require login to legacy portal | Use the original install media or contact Siemens representative for legacy SP media |
| License error: "WinCC flexible 2008 SP2 license not valid for SP3" | Floating license server enforces version match | Use the SP3 license on the upgraded Runtime, or downgrade the license authorization to SP2 |
Migration Path: WinCC Flexible 2008 → TIA Portal WinCC
Plants that need to break the SP juggling cycle permanently should plan a migration to TIA Portal V17/V18/V19 WinCC. The official migration tool converts *.hmi projects to *.ap18 / *.ap19 TIA projects, preserving screens, tags, alarms, and most scripts. The migration is best executed in a planned shutdown because:
- Some VBScript functions require manual review.
- Library references must be re-mapped to the TIA equivalents.
- Recipe structures may need re-import.
- PLC tag connections may need re-binding if the PLC program was also migrated.
The migration tool and prerequisites are documented in the Siemens WinCC Flexible migration portal. After migration, all future service packs are delivered through TIA Portal's unified installer, eliminating the per-SP juggling that triggers the original SP2/SP3 problem.
Verification Checklist After the Fix
- Runtime About dialog on HMI PC shows SP3 (V1.5.x.x).
- Project transfers without warnings or errors.
- All modified screens display correctly on the live HMI.
- All scripts and tag connections respond as expected.
- Alarms, recipes, and logs operate normally.
- Runtime event log is clean of "version mismatch" or "CRC error" entries.
- Backed-up
*.psbimage is stored in a known safe location.
Related Documentation
- Siemens Entry ID 28531852 — WinCC Flexible compatibility and version handling
- WinCC Flexible 2008 System Manual
- Migration from WinCC flexible to TIA Portal
- ProSave — backup and restore for WinCC Flexible Runtime
Frequently Asked Questions
Can WinCC Flexible 2008 SP3 ES download a project to an SP2 Runtime?
No. WinCC Flexible 2008 supports forward compatibility only. A newer ES cannot compile a project image targeted at an older RT, and the transfer dialog will show an empty project list. The fix is either to upgrade the Runtime to the matching SP or to use a separate SP2 ES (on real hardware or in a VM) to recompile and transfer.
Will "Save As Older Version" on the SP3 ES produce a transferable build?
No. Save As downgrades the source *.hmi file so it can be opened by an older ES, but it does not produce a compiled *.fwx Runtime image. The image must be rebuilt by an ES matching the target RT version.
How long does an in-place Runtime SP upgrade take on a PC-based HMI?
On a typical industrial HMI PC (Core i3/i5, 4 GB RAM, SSD), the in-place upgrade from SP2 to SP3 takes 20 to 40 minutes plus a 5-minute reboot. Cold-state installs on slower hardware can run to 60 minutes. The active project, recipes, and Runtime logs survive the in-place upgrade.
Can I run WinCC Flexible 2008 SP2 inside a Windows 10 or 11 virtual machine?
Yes, with caveats. WinCC Flexible 2008 SP2 is a 32-bit application and runs in a 32-bit Windows 7 SP1 VM under VMware Workstation, Hyper-V, or VirtualBox on Windows 10/11 hosts. The VM must have a bridged network adapter and USB passthrough for the MPI/Profibus PC adapter. Allocate at least 2 GB RAM and 40 GB disk.
What ports must be open between the ES and the HMI PC for Ethernet transfer?
Open UDP 6000 (primary transfer channel) and TCP 102 (ISO-on-TCP for S7 routing) between the ES and the HMI PC. Some plants also open TCP 1433 for SQL-based alarm logging replication. Restrict the rule to the engineering VLAN subnet to avoid exposing the control network.