WinCC Unified vs WinCC Classic: What’s New in Siemens’ Latest HMI Platform

Why WinCC Unified Is a Game Changer in Industrial HMI

The trend from legacy WinCC Comfort and WinCC Classic interfaces to WinCC Unified reflects a critical strategic pivot by Siemens: moving from proprietary runtime technology towards web-based standards as part of core components of industrial automation. This shift addresses current challenges with hardware scarcity of Comfort panels and meets increasing requirements for scalable, flexible visualization solutions in modern industrial environments.

WinCC Unified leverages web technologies such as HTML5, SVG, and JavaScript, enabling engineers and system integrators to create responsive, touch-optimized interfaces that scale from simple edge devices to full SCADA systems using a single codebase. This modern stack supports multi-platform deployment and distributed computing architectures, all of which are increasingly essential for Industry 4.0 and Industrial Internet of Things (IIoT) use cases.

In contrast, WinCC Comfort and other classic variants rely on proprietary C++ runtime frameworks tied closely to panel hardware, limiting future-proofing options. With Comfort panels facing end-of-life and maintenance difficulties due to hardware scarcity, Unified presents a sustainable migration path that preserves engineering investment while enhancing functionality.

The Technological Underpinnings: HTML5 and JavaScript vs. Proprietary Runtimes

WinCC Unified per official comparison guide leverages web technologies such as HTML5, SVG, and JavaScript, enabling engineers and system integrators to create responsive, touch-optimized interfaces that scale from simple edge devices to full SCADA systems using a single codebase. Unlike WinCC Comfort's C++ foundation, Unified uses an HTML5 web engine for rendering graphical elements, SVG for resolution-independent graphics, and JavaScript (ES6+) for scripting and logic.

This architecture enables responsive layouts that adapt to different screen sizes and orientations, native support for capacitive multitouch interfaces, gestures, and pinch-zoom, and cross-device and cross-platform compatibility, including PCs, industrial panels, and mobile devices.

WinCC Comfort uses raster graphics and resistive touch technology, limiting the fluidity and modern user experience achievable. Its VBA macro scripting requires external tools and is less performant and flexible compared to JavaScript event handling embedded directly into the HTML5 DOM.

Hardware Compatibility and Panel Models for WinCC Unified

HMI devices per Siemens PLC programming basics supporting each platform is an essential consideration for system integrators. WinCC Comfort panels—such as the KTP series—have been phased out progressively due to component shortages and outdated technology. In contrast, WinCC Unified supports the latest generation of dedicated HMI devices designed around web runtime environments.

Unified offerings include three main variants targeting different application complexities, mapped to panel types and usage scenarios:

WinCC Unified panels integrate seamlessly with S7-1500 controllers featuring integrated visualization capabilities, enabling distributed edge computing implementations. Industrial Edge containers further enhance flexibility, allowing containerized HMI deployment on edge nodes for decentralized processing.

Operator Experience: Responsive Design and Enhanced Interaction

WinCC Unified significantly improves operator interface design by introducing responsive layouts that adjust dynamically to different screen sizes and user interactions. The use of scalable vector graphics ensures crisp visuals on any display resolution, supporting pinch-to-zoom, swipe gestures, and multi-finger touch.

In contrast, the Comfort platform's fixed-position UI elements and resistive touch limit adaptability and fluidity. Operators can benefit from embedded screen windows with automatic scroll bars in Unified, making navigation through large projects more intuitive without permanently redesigning screens.

These innovations lead to improved usability, reduced operator fatigue, and lower training requirements—a critical factor in plants maintaining mixed legacy and modern equipment.

Advanced Navigation and Screen Management in WinCC Unified

Navigation within large projects is streamlined by Unified's architecture, which separates screens into distinct zones such as headers, content areas, and navigation panels. These zones maintain consistent user interfaces and facilitate project-wide styling and control.

Unified supports embedding screens larger than the physical display into 'window components' with automatic scroll bars, a feature absent in Comfort that required predefined screen sizes fitting the panel resolution. This flexibility allows complex operations to be visualized without simplifying or splitting views, helping operators maintain situational awareness.

Additionally, the unified main screen architecture standardizes navigation workflows, reducing engineering time spent on manual page linking and event creation, and improving overall system maintainability.

Scripting Evolution: JavaScript Replaces VBA Macros

The migration from VBA macros to JavaScript scripting in WinCC Unified marks a fundamental shift in HMI programming. JavaScript integrates natively with the HTML5 environment, enabling dynamic styling, event-driven logic, and asynchronous operations for better runtime performance.

JavaScript's modern language features such as ES6 modules and promises allow complex conditional logic and communication with backend systems through standard protocols like OPC UA to be implemented more cleanly than VBA's legacy approach. This improves maintainability and scalability of HMI applications.

However, this transition requires retraining engineering teams accustomed to VBA and can necessitate a rewrite of custom logic during migration.

Faceplates and Reusable Components: Increased Modularity

WinCC Unified supports advanced nested faceplates, allowing modular, reusable graphic components to be embedded within parent screens with full interactivity. This promotes code reuse, reduces engineering effort, and facilitates UI standardization across projects.

The Data2Unified conversion tool can partially convert legacy Comfort faceplates, primarily preserving visual elements, but manual re-linking of dynamic bindings and event handling is often necessary. Grouped objects and faceplate templates in Unified provide enhanced reuse mechanisms beyond what Comfort's static faceplates offered.

Migrating Projects with Data2Unified Conversion Tool

Siemens' Data2Unified add-in automates significant portions of the migration process, converting 50-90% of basic project elements depending on complexity. Key steps include importing legacy projects into TIA Portal, running the tool to convert screens, objects, and basic logic, then verifying and manually adjusting advanced items like alarms, trends, and VBA scripts.

This tool accelerates project baseline creation but does not produce immediately production-ready code; functionality testing, script rewriting, and UI refinements remain necessary.

Optimizing Performance and Scalability

WinCC Unified's web-based runtime architecture enables better utilization of modern multi-core processors and GPU-accelerated graphics compared to the monolithic C++ runtime of Comfort. Benchmarks show Unified PC runtime outperforming Comfort on equivalent hardware, especially in rendering and animation requiring motion control systems with PLCs.

Distributed deployment via Industrial Edge containers supports local processing on edge nodes, reducing latency and network dependencies inherent in centralized SCADA. Efficient use of global definitions and optimized variable storage avoids simulation artifacts common in legacy systems.

Security Improvements in WinCC Unified

Industrial cybersecurity measures are integrated natively in WinCC Unified. The platform offers consistent authentication mechanisms, encrypted communication channels, and compliance with industry standards. Contrast this with Comfort, which relied heavily on third-party patches and add-ons for equivalent security.

Integration with Industrial Edge further provides secure container isolation and automated update management, essential for maintaining secure, resilient industrial environments.

Comprehensive Migration Pathways for Plants and OEMs

Migration to WinCC Unified can follow several approaches depending on project size and requirements:

• Full Conversion: Using Data2Unified tool to migrate entire Comfort projects to Unified.
• Greenfield Projects: Designing new systems from scratch with Unified for maximum benefit.
• Hybrid Architectures: Parallel operation of legacy Comfort panels alongside new Unified devices during transition phases.

Typical migration timelines range from 2 to 8 weeks, influenced by project complexity and amount of faceplate or script rework needed.

Hardware and System Requirements Comparison

Evaluating system specifications is vital for proper deployment planning:

Version History and Feature Evolution

Siemens has released multiple Unified platform versions—V16, V17, and the current V18—each expanding functionality and increasing system limits. Earlier versions are sufficient for smaller projects but lack advanced features like nested faceplates and improved security options.

Understanding version-specific capabilities enables integrators to select the optimal software base aligned with project goals and long-term maintenance plans.

Planning Training and Support for Engineering Teams

The transition from Comfort to Unified requires skill upgrades in JavaScript programming, web-based UI design, and container deployment. Vendors and the Siemens support community provide extensive resources including documentation, forums, and training courses to facilitate upskilling.

Investing in training ensures smoother migrations, higher code quality, and the ability to leverage full Unified platform benefits from the Siemens collection.

Conclusion: Strategic Modernization for Future-Proof HMI Systems

For automation engineers, system integrators, and OEMs, adopting WinCC Unified aligns visualization platforms with current and emerging industrial IT paradigms. Its based-on open web standards runtime, scalable distributed architecture, and modern user experience capabilities address the limitations and end-of-life risks inherent in WinCC Comfort hardware and software.

While the conversion requires careful planning, tooling, and script rewriting, the cost-benefit balance favors long-term reliability, security, and flexibility gains. Combined with Industrial Edge deployment options and multi-tier hardware support, WinCC Unified positions industrial operators to optimize interfaces, reduce downtime, and integrate seamlessly into Industry 4.0 environments through partners like Leadtime.