Changing Default Font in WinCC Unified: V17 to V20 Guide

Overview

WinCC Unified uses a built-in style sheet that controls typography, color, margins, and the visual appearance of every screen object created from the toolbox. The default font is part of that built-in style and is therefore not editable from the standard TIA Portal configuration UI in TIA Portal V17 and V18. Beginning with TIA Portal V19, Siemens introduced the SIMATIC WinCC Unified Corporate Designer, an add-on that lets you replace the built-in style with a project-specific style, including the default font. This article documents every supported path to change font behavior in WinCC Unified from V17 through V20, why the Fallback Font column is grayed out in some configurations, and which workarounds apply when Corporate Designer is not licensed.

Where Font Settings Live in the Project Tree

Font-related configuration in a WinCC Unified device is split across three editors in the TIA Portal project tree:

1. Project languages → Languages & resources – defines the runtime languages, the language-dependent font, and the resource files that ship with the project.
2. Runtime settings → Language & font – defines the active runtime language, fallback chain, default font, and Unicode behavior at runtime.
3. Screen object properties → Appearance → Font – per-object font override that takes precedence over the runtime default for the affected object only.

Each editor solves a different problem. The project language table decides which font accompanies which translation. The runtime settings table decides what font the HMI uses when the active language is not the project default. The screen property decides what font a single label, button, or text box shows. None of these editors edits the global default font that is assigned automatically to a brand-new screen object placed from the toolbox.

Runtime Settings → Language & Font Reference

The editor at Runtime settings → Language & font exposes the following columns. Documented behavior follows the TIA Portal V20 reference for RT Unified.

The grayed-out Fallback Font cell that operators see in the default installation is by design. The cell becomes writable only after the project has been linked to a Corporate Designer style that exposes a fallback slot. Without a style override, the built-in fallback is hard-coded to Segoe UI on Windows panels and Roboto on Unified Comfort Panels, and Siemens does not expose a configuration entry for it. See the official Language & font (RT Unified) page for the V20 reference.

Built-in Style Versus Custom Style

Every WinCC Unified project ships with one of two style backbones:

• Built-in style – Compiled into the runtime; cannot be modified, replaced, or extended. This is the only style available in TIA Portal V17 and V18.
• Custom style (Corporate Designer) – Authored in the SIMATIC WinCC Unified Corporate Designer add-on, exported as an .sds file, and imported into the Unified device. The custom style can override the default font, default size, default margin, default corner radius, and the complete color palette. Available from TIA Portal V19 onward.

Configuring the Default Font Without Corporate Designer (V17, V18)

If you are still on V17 or V18, the default font assigned to new screen objects cannot be changed. Use the following procedure to apply a different font to every text-bearing object in the project:

1. Open the Project tree → Devices → [Unified device] → Screens.
2. Select the first screen, press Ctrl + A to select all screen objects.
3. In the Inspector window, expand Properties → Appearance → Font.
4. Uncheck the Inherit check-box on the font family row.
5. Pick the new font (for example Arial, Tahoma, or a corporate font shipped in the Windows image).
6. Right-click the screen name in the project tree and choose Copy properties of font, then paste the property to every other screen in the device.
7. Compile the device and download to the panel or PC runtime.

For projects with many screens, write a small script in the TIA Portal Openness API that walks every HMIScreen object and sets FontFamily programmatically. A minimal C# example:

using Siemens.Engineering;
using Siemens.Engineering.Hmi;
using Siemens.Engineering.Hmi.Screen;

var tia = new TiaPortalProcess(true);
var project = tia.GetProject() ?? tia.Projects.Open(new FileInfo(@"C:\\Projects\\MyPlant.ap20"));
var device = project.Devices.First(x => x.Name == "HMI_RT_1");
var hmiDevice = (HmiDevice)device;

foreach (var screen in hmiDevice.Screens)
{
    foreach (var element in screen.ScreenItems)
    {
        if (element is IText text)
        {
            text.Font.Family = "Arial";
            text.Font.Size = 14f;
            text.Font.Bold = false;
        }
    }
}
project.Save();

Adding Custom Fonts to the Runtime (Own Fonts)

Whether or not you switch the default style, any font that is not present in the Windows or panel image must be packaged with the project. The editor is Runtime settings → Language & font → Own fonts. Documented in the Own fonts (RT Unified) reference.

1. Acquire the font in .ttf or .otf form. Confirm the licensing permits redistribution inside the runtime image.
2. In TIA Portal, navigate to Runtime settings → Language & font and switch to the Own fonts tab.
3. Click Add and select the font file. The font is registered by its internal family name, not by the file name.
4. Assign the font to one or more runtime languages. A font can be the default for a language or a fallback for missing glyphs.
5. Compile the device. The font file is copied into the \Fonts subfolder of the generated runtime and registered on first start.

SIMATIC WinCC Unified Corporate Designer (V19+)

Corporate Designer is the only path that genuinely replaces the default font for new objects without per-screen scripting. The add-on installs as a separate TIA Portal option package and is licensed per seat or per floating license.

Workflow

1. Install the Corporate Designer add-on from the Siemens online software delivery portal. The version number must match the TIA Portal version (V19, V19 Update 1, V20, and so on).
2. Create a new Style project in the Corporate Designer start screen.
3. In the Typography editor, change the Default family to the corporate font, adjust the size scale, and define the fallback chain.
4. Export the style as MyCorporateStyle.sds.
5. Return to the TIA Portal project, open the Unified device, and choose Runtime settings → Corporate Designer → Import style.
6. Compile. New screen objects will use the imported default font. Existing objects keep the font assigned at creation time unless you reset their style.

Style Slot Reference

Per-Object Font Override

When a corporate-wide change is not feasible, override the font on individual screen objects. The Inspector exposes the following controls under Properties → Appearance → Font:

• Family – dropdown of every font registered in the active style plus every font listed under Own fonts.
• Size – numeric in points; the style scale is ignored once a value is set explicitly.
• Bold / Italic / Underline / Strike-through – bitmask.
• Inherit from style – when checked, the field is bound to the parent style slot. Uncheck to pin the value.

Pin values on critical readouts (numeric values, alarm text) so that future style imports do not change their typography. Leave dynamic and decorative elements on the inherited setting so they pick up the new default automatically.

Verification Procedure After a Font Change

After you change the default font (or import a new Corporate Designer style), verify the change has propagated correctly:

1. Compile the Unified device in TIA Portal and review the Compile log for warnings about missing fonts, broken inheritance, or style conflicts.
2. Start the WinCC Unified Runtime Simulator on the engineering PC. The simulator uses the same style backbone as the panel, so it is the fastest way to preview changes.
3. Place a new Text field and a new Button on a sandbox screen. Confirm that both use the new default font without manual editing.
4. Open an existing screen, select a previously placed text object, and verify in the Inspector that the font row still shows the original family. The new style should not have overwritten pinned values.
5. Switch the runtime language between at least two configurations (for example, German and Simplified Chinese) to confirm the fallback chain is honored and that no glyphs are rendered as □ tofu boxes.
6. Download to the target panel, perform a power-cycle, and confirm the new font persists across reboots.

Troubleshooting Matrix

Migration Notes from V17/V18 to V19/V20

When a project is upgraded from TIA Portal V17 or V18 to V19 or V20, the built-in style continues to apply. The first time you import a Corporate Designer style into an upgraded project, every screen is recompiled against the new style backbone. Expect the following:

• Backup the project before the upgrade. The TIA Portal upgrade wizard writes a *.ap17.bak or *.ap18.bak file alongside the original.
• Document the font of every text-bearing object in the pre-upgrade project. The build-in style uses Segoe UI; if the post-upgrade style uses a different default, the visual diff will be obvious.
• Schedule the upgrade during a plant shutdown because the first download of the new style forces a full screen refresh on the panel.
• Verify the alarm control, trend control, and report templates because those controls rely on the header and body slots, not the body slot alone.

Field-Proven Caveats

• Siemens does not provide a registry or group-policy hook that changes the built-in default font outside Corporate Designer. Attempts to patch the runtime DLLs break the Siemens software license agreement and the runtime digital signature.
• The Microsoft default font configuration for Office is unrelated; it sets the Office user default, not the WinCC Unified built-in style.
• On Unified Comfort Panels (MTP/MTP-II), the firmware version must be at least the same major as the TIA Portal version. A V20 style loaded onto a panel running V18 firmware will fall back to the built-in style and log a style-bind warning in the panel diagnostic log.
• Custom fonts that reference external resources (for example, web fonts loaded over HTTP) are not supported in the runtime. Bundle the font file in the project.

Frequently Asked Questions