Configuring Widescreen Resolutions in WinCC Flexible PC RT

Siemens WinCC Flexible PC Runtime was, for nearly a decade, the standard HMI visualization platform for SIMATIC panel projects running on industrial PCs. The platform shipped with a fixed, finite list of screen resolutions — every entry being a 4:3 aspect-ratio mode designed for the CRT monitors and early LCD panels common when the product was architected. As 16:9 and 16:10 widescreen LCDs replaced 4:3 displays in operator consoles, kiosks, and exhibition hardware, the resolution ceiling of PC Runtime became a real engineering problem. Circles render as ovals, text is stretched, and full-screen mode forces either pillarboxing or a stretched image that destroys UI legibility.

This reference covers the resolution matrix shipped with each WinCC Flexible release, the widescreen modes introduced in Service Pack 2 for WinCC Flexible 2008, configuration steps for setting PC RT resolution, workarounds for monitors that still fall outside the supported list, and the migration path to TIA Portal WinCC RT Advanced / RT Professional where arbitrary resolutions and multi-monitor layouts are first-class citizens.

1. WinCC Flexible PC RT Resolution Architecture

WinCC Flexible PC Runtime is a 32-bit Windows application that opens a single top-level window on the host display. The window is created at a fixed pixel size selected from a hard-coded enumeration. The runtime does not query the connected display's EDID for native timing, does not consult the GPU for custom modelines, and does not perform any internal scaling. Consequently, the only way to obtain a clean 1:1 pixel mapping is to select a resolution that exactly matches the panel's native timing.

Three architectural constraints matter to the field engineer:

• Fixed resolution list. Width and height cannot be changed outside the offered resolutions. Attempts to set width or height via VBScript at screen-loading time are silently ignored; the runtime recreates the window at the configured size on every cycle.
• No GPU scaling awareness. If the host OS reports a non-native timing and the GPU performs the upscale, the application still draws at its own pixel grid. Aspect mismatch in the OS scaling path will produce ovals from circles and stretched text.
• Single window, no DPI virtualization. PC RT is not DPI-aware. A project designed for a 1280x1024 panel will not auto-redraw for a 1920x1080 panel; layout coordinates are absolute.

2. Original 4:3 Resolution Matrix (WinCC Flexible 2005 / 2007 / 2008 pre-SP2)

The PC Runtime installer registers the following resolutions with the configuration dialog. All are 4:3 or 5:4 aspect ratio; no widescreen mode is present in the base release.

Common 16:9 / 16:10 timings found on commercial and exhibition hardware — 1366x768, 1440x900, 1680x1050, 1920x1080, 1920x1200 — are absent from this list. Selecting full-screen mode on a 16:9 monitor while the runtime is locked to 1280x1024 forces the GPU to perform a non-uniform stretch, which is the visible source of the oval-from-circle distortion operators report.

3. WinCC Flexible 2008 Service Pack 2 — Widescreen Support

Siemens Product Management released Service Pack 2 for SIMATIC WinCC flexible 2008 specifically to add widescreen timing to PC Runtime. SP2 is a delivery release and must be installed on top of an existing WinCC flexible 2008 engineering station and on every PC Runtime target. SP2 does not change the maximum number of simultaneously open screens, the project size limit, or the supported Comfort / Panel PC firmware.

After SP2 is applied, four new resolutions appear in the PC RT resolution selector:

4. Configuring Screen Resolution in WinCC Flexible 2008 SP2

Resolution selection lives in the HMI device's PC Runtime settings, not in the screen editor. The procedure is identical for SP1 and SP2; only the available values change.

1. Open the WinCC flexible ES project.
2. In the project tree, right-click the PC Runtime HMI device node and select Device Properties.
3. Switch to the Runtime tab in the dialog.
4. Locate the Screen resolution drop-down. In pre-SP2 builds the list contains only the five 4:3 / 5:4 modes. After SP2 installation the list extends to nine modes including the four widescreen entries above.
5. Select the target resolution, e.g. 1920 x 1080.
6. Compile the project with Project > Compiler > All and transfer the runtime to the PC RT target.
7. On the target, open the transferred project, set the runtime to full-screen, and verify that the OS mode set is also 1920x1080 to prevent double-scaling.

5. Aspect Ratio Distortion and Correction

Aspect distortion has two distinct sources and they are not interchangeable.

5.1 Source A — Runtime at one aspect, panel at another

WinCC Flexible PC RT renders into a window sized 1280x1024 (5:4). The connected display is a 16:9 panel with native 1920x1080. The Windows display driver performs the upscale. Because 5:4 and 16:9 are not the same ratio, the driver has to either letterbox / pillarbox the image or stretch it non-uniformly. Non-uniform stretch is the default on most consumer panels, which is what produces ovals from circles. The fix is to set the runtime resolution to match the panel's aspect exactly: 1920x1080 on a 16:9 panel, 1920x1200 on a 16:10 panel.

5.2 Source B — Project designed at one aspect, runtime forced to another

If the original WinCC flexible project was authored for a 1280x1024 (5:4) screen, the absolute coordinates of every object assume that grid. Re-targeting the runtime to 1920x1080 (16:9) produces extra horizontal space but does not redistribute objects automatically. Operators see the original screen with letterbox bars on the left and right. Two corrective actions are possible:

• Re-lay out the screens. Re-author screens at the new resolution using the screen editor's grid; rebuild the project.
• Use horizontal scrolling on the screen object. Configure the screen as a single oversized canvas in the project and let runtime window sizing expose it — useful only if the new resolution is taller than the original.

6. Workarounds for Resolutions Outside the Supported List

Custom modelines are not supported, but several field-proven approaches produce an acceptable image on resolutions such as 1366x768, 2560x1440, or 3840x2160.

6.1 Closest-mode selection

Pick the closest supported resolution with the same aspect ratio and let the panel perform its own internal scaler. For 1366x768 (16:9), the closest 16:9 mode is 1920x1080; the GPU downscales 1920x1080 to 1366x768 with a uniform stretch. Modern panels with a 1:1 pixel mapping option in the OSD can be set to "1:1" or "aspect" to preserve geometry. The result is a slightly soft image but with correct aspect.

6.2 Windowed mode with borderless chrome

Run PC RT in windowed mode and strip the title bar with a third-party tool such as Windowed Borderless Gaming or a custom Win32 SetWindowLong(hwnd, GWL_STYLE, WS_POPUP) shim. The OS then handles the mode set natively; the runtime window can be sized freely within the desktop. The drawback is that Alt+Tab exposes the OS taskbar unless an autohide / kiosk shell is configured.

6.3 Custom OS resolution via GPU control panel

NVIDIA Control Panel, AMD Radeon Settings, and Intel Graphics Command Center all support custom resolutions / custom modelines. A 1366x768 timing can be added to the driver. WinCC Flexible cannot be configured to request this timing, so this approach is only useful when the host OS itself is set to the custom timing before PC RT starts — and the runtime resolution selector is parked on any 16:9 mode for aspect purposes. Geometry is preserved because the panel receives its native timing.

6.4 Virtual display driver

Tools such as USB Display Adapter (DisplayLink) or virtual display drivers present a fixed EDID with a chosen timing. This is appropriate for headless PC RT deployments where no physical panel is attached at engineering time but the final exhibit hardware requires a non-standard mode.

7. Migration to TIA Portal: WinCC RT Advanced / RT Professional

For new projects, or for projects where the resolution constraint is the binding issue, the recommended path is migration to TIA Portal and the use of WinCC RT Advanced or WinCC RT Professional. Both runtimes allow the resolution to be specified freely in the device configuration, and RT Professional additionally supports multi-monitor layouts, faceplates, and arbitrary DPI scaling.

For migration of a WinCC flexible project, use the TIA Portal Migration tool that ships with TIA Portal V13 and later. Screen objects, tag connections, alarm logs, and recipes are carried over; absolute coordinates are preserved and re-interpreted against the new device's resolution. Re-compile the migrated project and re-validate every screen against the new aspect ratio.

8. Configuring Screen Resolution in TIA Portal (RT Advanced)

Per the official Siemens documentation at Changing the screen resolution (RT Advanced), the resolution of a WinCC RT Advanced runtime is configured in the HMI device's Runtime settings.

1. Open the TIA Portal project.
2. In the project tree, select the HMI device (RT Advanced target).
3. Open Runtime settings from the device's properties.
4. Select the Screen category.
5. Change the Screen resolution entry to the target timing. Unlike WinCC flexible, the field accepts any value within the runtime's supported timing range (typically 640x480 up to 1920x1080 on RT Advanced, up to 4K on RT Professional).
6. Compile and download.

For RT Professional, the resolution is set in the WinCC Explorer under Computer properties > Graphics runtime > Window properties. Multiple monitors are configured under Monitor configuration, with each monitor receiving its own resolution and position.

9. Disabled Button Visualization

A separate but related WinCC flexible UX issue is the absence of a "grayed out" appearance for disabled buttons. In the full WinCC (not WinCC flexible) runtime, buttons whose Enabled property is false automatically render with a desaturated / dimmed style. In WinCC flexible PC RT, the disabled state is indicated only by a small lightning-bolt icon next to the mouse cursor when the button is hovered. Operators who do not hover have no visual cue.

Two compensating techniques are standard practice:

• Two-graphic button with conditional visibility. Configure the button as a graphic object with two graphics (enabled / disabled). Bind visibility of each graphic to a tag that mirrors the Enabled state. Operators see a visually distinct disabled graphic.
• Animation: Appearance > "Disable" property. For symbolic graphics, use the Appearance animation to drop opacity to 50% when the Enabled tag is false.

10. Field Commissioning Checklist for Widescreen PC RT

1. Confirm WinCC flexible 2008 SP2 (or later) is installed on both the engineering station and the PC RT target. Open Help > About and verify the build number.
2. Confirm the target display's native timing. Read it from the EDID via MonitorInfoView or the panel's spec sheet.
3. Select a runtime resolution in WinCC flexible that exactly matches the panel's aspect (16:9 or 16:10). Use the table in §3 to pick the closest mode.
4. Set the Windows display mode to the same resolution. Disable any "GPU scaling" option that forces non-uniform stretch.
5. Set the panel's OSD to 1:1 pixel mapping or aspect — never stretch.
6. Render the test screen with at least one circle (e.g. a 100 px radius filled circle). Verify visually that the circle is round, not oval. If oval, the OS or panel is still performing a non-uniform stretch; revisit steps 4–5.
7. Verify disabled-button legibility using the technique in §9.
8. Document the resolution, panel model, OSD settings, and GPU driver version in the project README for the next maintainer.

11. Troubleshooting Matrix

12. Frequently Asked Questions