Problem Description
WinCC Flexible 2008 RT installed on a Windows 8 tablet PC (7-inch display) exhibits a specific symptom: the built-in on-screen keyboard does not register keystrokes when keys are pressed via touch input. However, the same keyboard functions correctly when using an external USB mouse. Additionally, the Windows native virtual keyboard works correctly when manually opened, but this requires exiting WinCC Flexible RT and minimizing the application to access Windows keyboard inputs—a workflow that disrupts operator efficiency.
Root Cause Analysis
The issue stems from how WinCC Flexible 2008's on-screen keyboard component interacts with Windows 8's touch input system, specifically when Windows is operating in Tablet Mode. In Tablet Mode, Windows alters how touch inputs are processed and routed to applications, and WinCC Flexible 2008's virtual keyboard (designed primarily for traditional HMI operator panels) does not properly intercept these modified touch events.
This is a known compatibility limitation between WinCC Flexible 2008 (released circa 2008) and the Windows 8/8.1 touch architecture introduced nearly five years later. The mouse input path works because it uses the standard Windows input queue, while touch input follows a different code path that the older WinCC Flexible runtime does not fully support.
Solution
Primary Fix: Disable Windows Tablet Mode
- Swipe in from the right edge of the screen to access the Windows Charms menu
- Click Settings
- Click the Tablet Mode toggle to turn it OFF
- Test the WinCC Flexible on-screen keyboard via touch input
Once Tablet Mode is disabled, the touch input should route correctly to the WinCC Flexible on-screen keyboard.
Alternative Workaround: Use Windows Native Keyboard
If Tablet Mode must remain enabled, configure Windows to use the native virtual keyboard instead of WinCC Flexible's built-in keyboard:
- Navigate to Control Panel → Hardware and Sound → Tablet PC Settings
- Click Other in the left navigation pane
- Uncheck Turn on Tablet PC components for other programs
- Apply and restart WinCC Flexible RT
Alternatively, users can press Win + R and type osk to launch Windows On-Screen Keyboard manually, though this requires the workflow adjustment noted in the original problem statement.
Verification
After implementing either solution:
- Open WinCC Flexible 2008 Runtime
- Tap any input field that triggers the on-screen keyboard
- Verify keystrokes register when pressing keys via touch
- Confirm input appears correctly in the target field
Compatibility Notes
Related Configuration Parameters
| Setting | Location | Expected Value for Touch Fix |
|---|---|---|
| Tablet Mode | Windows Settings → System → Tablet Mode | OFF |
| Touch Keyboard Visibility | WinCC Flexible → Project Settings | Auto (default) |
| Touch Input Routing | Windows Control Panel → Tablet PC Settings | System default enabled |
FAQ
Why does WinCC Flexible 2008 on-screen keyboard work with mouse but not touch?
WinCC Flexible 2008 uses older input handling that routes mouse clicks through the standard Windows message queue, while touch inputs in Tablet Mode follow a different path (WM_POINTER messages) that the 2008 runtime does not fully process.
Does this issue occur on Windows 10 tablets?
Yes, similar behavior may occur on Windows 10, especially on devices with Tablet Mode enabled. The same fix (disabling Tablet Mode) typically resolves the issue.
Can I use Windows native keyboard instead of WinCC Flexible keyboard?
Yes, but this requires manually opening the Windows keyboard and does not integrate seamlessly with WinCC Flexible input fields. Automatic switching requires system-level configuration changes.
Is there a firmware or patch to fix this in WinCC Flexible 2008?
No. This is a fundamental architecture limitation of WinCC Flexible 2008's touch handling, not a bug that was patched. The product is in legacy status; consider upgrading to WinCC (TIA Portal) for modern tablet support.