Resolving WinCC Unified PC V19 Runtime Touch Screen Lockup

Problem Description

A WinCC Unified PC V19 Runtime installed in Kiosk mode of the SIMATIC WinCC Unified Station Configurator exhibits a recurring fault: the touch screen on the panel PC stops accepting input approximately once per week, while the underlying Windows operating system (mouse pointer, on-screen keyboard, Start menu, and physical peripherals) continues to respond normally. The recovery is to terminate and relaunch the Kiosk Runtime display — typically with Ctrl + F4 on the attached physical keyboard — without restarting the project in the SIMATIC Runtime Manager or rebooting the PC.

The fault is observed in a food-processing cell where the panel is subjected to nightly washdown with water spray. The recurrence interval suggests a cumulative resource issue inside the Kiosk session (memory leak, COM port handle exhaustion, ghost touch events from capacitive pooling, or browser-engine tab corruption) rather than a one-time crash.

WinCC Unified PC V19 Runtime Architecture

Understanding the runtime stack is essential before chasing the fault. The Kiosk presentation on a PC-RT host is not a native Win32 application — it is an HTML5 / Chromium-based renderer launched inside a dedicated session by the SIMATIC WinCC Unified Station Configurator.

Touch events enter the OS through the HID stack, are translated into WM_POINTER messages, and forwarded to the foreground window. When the Kiosk window owns the foreground, those pointer messages are mapped to HTML pointerdown / pointerup events by the embedded Chromium engine. If any layer between the HID driver and the renderer drops, freezes, or stops consuming messages, the user observes exactly the symptom described: Windows desktop still responsive (because explorer.exe and the cursor driver are alive), but the Kiosk surface is dead.

Root Cause Analysis

Four root-cause classes are consistent with the reported behaviour. Treat the list as a decision tree, not a guess list.

1. Defect in WinCC Unified V19 Kiosk Engine (Pre-Upd3)

Siemens released TIA Portal V19 Update 3 (V19.0.3) in early 2024 and shipped a matching WinCC Unified PC Runtime Update 3 together with a Station Configurator Update 3. The configurator update specifically addresses Kiosk-mode stability, session restart, and touch input handling on PCRT hosts. Field reports on the Siemens Industry Online Support portal (SIOS entry ID 109825527) document that hosts running V19 base or V19 Upd1/Upd2 can exhibit Kiosk window freeze after sustained uptime (typically 5–14 days). The Upd3 configurator patches the underlying Chromium host integration.

2. Washdown-Induced Ghost Touch / Pointer Flood

Capacitive and projected-capacitive (PCAP) touch sensors exposed to conductive water film on the glass surface generate a high rate of ghost WM_POINTER messages. The browser event loop on the Kiosk surface can saturate trying to dispatch those to the active page, especially if a screen has an aggressive timer or polling. Symptoms mimic a hang because the page never yields control back to the user input handler.

3. Memory Leak in Long-Running Kiosk Session

The Chromium renderer used by the Station Configurator accumulates GPU and JavaScript heap over time when the same session is not reloaded. Weekly recurrence is a strong signature of a leak in the megabyte-per-hour range — well within the documented failure profile of older Chromium Embedded Framework (CEF) integrations on Windows.

4. USB / HID Touch Driver Reset

Some industrial touch controllers (Elo, 3M MicroTouch, Advantech, Hope Industrial) require a device reset when exposed to repeated ESD events from cleaning equipment. The OS HID stack marks the device as disconnected, after which the browser never receives new pointer messages. Mouse and keyboard remain on a different HID collection and are unaffected — which is exactly what the operator reports.

Diagnostic Procedure

Run the following checks in order. Each step is non-destructive and can be performed on the live system.

1. Confirm the OS touch stack is alive. Open devmgmt.msc, expand Human Interface Devices, and verify the touch device is enabled with no yellow bang. In Device Manager → View → Devices by connection, walk the USB / I2C tree to confirm the controller reports no Code 43 or Code 10.
2. Confirm the Kiosk process is still running. Open Task Manager → Details and look for Siemens.Simatic.WinCCUnifiedConfigurator.exe and the child msedgewebview2.exe or CEF process associated with the Kiosk window. CPU should be <5 % idle. A process at 0 % CPU with the window frozen indicates renderer deadlock, not a driver issue.
3. Capture the renderer state. Right-click the Kiosk window title (if reachable through a hot-corner) and select Inspect to open Chromium DevTools. In the Memory tab, snapshot the heap; compare against a baseline taken on a freshly started session. Growth > 50 % per day indicates a JS leak.
4. Read the Kiosk log directory. Open C:\ProgramData\Siemens\Automation\WinCCUnified\StationConfigurator\Log\ and inspect the most recent .log. Look for repeated JavaScriptException, RendererHang, GPU process exited, or PointerMessageQueue overflow entries.
5. Check installed update level. Open Start → Apps & Features and read the version of "SIMATIC WinCC Unified Station Configurator". Anything earlier than 19.0.3.0 is on the vulnerable baseline.
6. Check for touch device disconnect events. Open eventvwr.msc → Windows Logs → System and filter for sources Kernel-PnP and DeviceSetupManager near the time of the freeze. Events 411, 20001, or 20003 indicate a HID touch controller that was unplugged by the stack.

Solution A: Apply TIA Portal V19 Update 3 and Unified PCRT Update 3

The first action is to bring the entire toolchain to the same patch level. Mismatched versions of TIA, the Station Configurator, and the WinCC Unified PCRT are the most common cause of Kiosk instability.

1. On the engineering station, install TIA Portal V19 Update 3 via the Siemens Automation Update Tool or the SIMATIC Software Installer. The package is the SIMATIC_TIA_Portal_V19_UPD3 delivery.
2. On the panel PC, install SIMATIC WinCC Unified PC Runtime V19 Update 3. This updates Siemens.Simatic.WinCCUnifiedRT.exe and the supporting services.
3. On the panel PC, install the matching SIMATIC WinCC Unified Station Configurator Update 3. This updates the Chromium host integration and the Kiosk window manager.
4. Rebuild and download the project from the engineering station so the runtime is loaded with a V19.0.3-compatible image.
5. Restart the panel PC once after the upgrade so all services are re-registered.

Solution B: Configure a Scheduled Task to Restart the Kiosk Surface

Even after Upd3, the operator should implement a defensive restart. A nightly taskkill of the configurator and a relaunch through the SIMATIC Runtime Manager provides a clean CEF session every 24 hours and is the single most effective mitigation against the leak class of faults.

1. Create a PowerShell script C:\Maintenance\Restart-WinCCKiosk.ps1 with the following content:

   $cfg = "Siemens.Simatic.WinCCUnifiedConfigurator.exe"
   Get-Process -Name $cfg -ErrorAction SilentlyContinue | Stop-Process -Force
   Start-Sleep -Seconds 5
   Start-Process -FilePath "C:\Program Files\Siemens\Automation\WinCCUnified\StationConfigurator\Siemens.Simatic.WinCCUnifiedConfigurator.exe" `
                 -ArgumentList "-kiosk" -WindowStyle Normal
   

2. Open taskschd.msc on the panel PC and create a new task named WinCC_Kiosk_Nightly_Restart.
3. In the General tab: select Run whether user is logged on or not, and Run with highest privileges.
4. In the Triggers tab: schedule the task daily at the start of the washdown window (e.g., 02:30).
5. In the Actions tab: Start a program → powershell.exe with arguments -ExecutionPolicy Bypass -File C:\Maintenance\Restart-WinCCKiosk.ps1.
6. In the Conditions tab: uncheck Start the task only if the computer is on AC power (industrial PCs are normally on AC).
7. In the Settings tab: enable If the task fails, restart every and Attempt to restart up to 3 times.

Solution C: Harden the Kiosk Window for Washdown

To reduce ghost-touch storms during the washdown window:

• Enable the touch driver's Water Rejection / Wet Touch mode in the controller's utility (Elo Tune, 3M MT7, Advantech Monitor Tools). On PCAP panels this is usually a single checkbox in the OSD or the manufacturer utility.
• Reduce the pointer message rate by enabling Touch Suppression in the touch driver's advanced properties, or by setting the registry value HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HidInput\Parameters\MaximumPointerMessages to 400 (decimal) on Windows 10 1903+.
• Schedule the washdown to occur only while the Kiosk surface is in a screen saver / blank state. The WinCC Unified Station Configurator exposes the parameter ScreenSaverActivationTime in the project; set it to 60 s of idle.
• Verify the panel's IP / NEMA rating matches the washdown environment. A typical food-zone panel must be at least IP65 / NEMA 4 on the front face, and the touch surface must be rated for direct spray.

Solution D: Force Window Refresh from the Configurator

If the operator is at the panel and touch is dead but the mouse works, you can refresh the Kiosk window without rebooting the runtime. The technique is to send a WM_CLOSE to the configurator window and immediately relaunch it through the SIMATIC Runtime Manager.

1. Attach a USB keyboard.
2. Press Ctrl + F4 to close the Kiosk window. The configurator host remains running; only the renderer exits.
3. In the taskbar, right-click the SIMATIC Runtime Manager tray icon and select Start Runtime. The configurator will reopen the Kiosk surface with a fresh Chromium session.
4. If the keyboard is unavailable, RDP into the panel PC (port 3389) from the engineering station and perform the same three steps remotely.

Verification

After applying Solution A and Solution B, verify the fix with the following checks.

Monitoring and Long-Term Stability

For production lines that cannot tolerate a weekly manual reset, deploy a watchdog that monitors the Kiosk process and triggers the same PowerShell script in Solution B on heartbeat loss. A minimal watchdog is a second scheduled task running every 15 minutes that:

1. Queries Get-Process -Name "Siemens.Simatic.WinCCUnifiedConfigurator.exe".
2. Checks that the MainWindowTitle matches the configured project name (a frozen renderer keeps the title but the process never advances its render tick).
3. If the title is missing or the process CPU is exactly 0 % for two consecutive samples 5 minutes apart, invokes the restart script.

Pair the watchdog with the SIMATIC WinCC Unified Performance tags in the project (e.g., @SystemPerfCounter_TotalCPU and @SystemPerfCounter_AvailableMBytes) and archive them in the WinCC Unified log so you can see the leak curve trending upward days before the freeze. Reference Siemens' WinCC Unified V19 System Manual entry ID 109825527 on SIOS for the canonical tag list and diagnostic flow.

Escalation Path

If the symptom persists after Upd3 and a 24-hour automated restart, raise a Siemens Technical Support ticket with the following artefacts:

• Full content of C:\ProgramData\Siemens\Automation\WinCCUnified\StationConfigurator\Log\ covering at least 7 days.
• Task Manager export of the configurator and child processes during a frozen state.
• Output of msinfo32 /report from the panel PC.
• TIA project SHA-256 hash and the V19 patch level of TIA, PCRT, and Station Configurator.
• Photograph of the touch device entry in Device Manager showing the hardware ID and driver version.

Reference the support request number internally against SIOS entry 109825527 and the WinCC Unified V19 release notes (entry 109815720) for the exact set of fixed defects in each cumulative update.

Safety and Operational Notes

FAQ