Electromobility is evolving rapidly. New vehicle concepts, complex E/E architectures, and increasingly powerful battery systems are pushing developers to their limits. At the same time, the pressure to shorten development cycles and reduce costs is growing. In this dynamic environment, one method is gaining significant traction: Software-in-the-Loop (SIL) testing.

What Is Software-in-the-Loop Testing?

SIL testing refers to the virtual validation of ECU functions using simulation models—without any physical hardware. The ECU software runs in a virtual environment and interacts with a digital twin of the vehicle or subsystem. This allows engineers to test functions early, identify errors, and reduce development risks.

Why SIL for Battery Electric Vehicles?

Battery electric vehicles (BEVs) are particularly complex: battery management systems (BMS), charging functions, thermal management, and energy management must work seamlessly together. SIL testing enables:

• Early validation of control algorithms, such as for energy management, charging, and thermal management.
• Simulation of charging infrastructure and smart charging, including communication protocols like ISO 15118-20.
• Testing of Battery Management Systems (BMS), Simulation of cell behavior and fault conditions to validate safety and efficiency algorithms.
• Integration of new E/E architectures, such as zonal controllers or centralized vehicle computers.

Advantages Over Traditional Testing Methods

SIL testing is especially powerful in early development phases. It supports parallel testing, automated regression testing, and seamless integration into CI/CT pipelines. Its scalability allows teams to run thousands of test cases across multiple virtual environments simultaneously, while virtualization enables testing of entire software stacks—including middleware and operating systems—without the need for physical ECUs. The full potential of SIL unfolds through its scalability in cloud applications, which enables the parallelization of tests and thus increased test coverage and speed.

New E/E Architectures: Challenges and Opportunities

Modern vehicles increasingly rely on zonal architectures, where functions are centralized rather than distributed across individual ECUs. This brings benefits in terms of weight, cost, and update capability—but also introduces new validation challenges like modelling the hardware dependencies of ECUs.

SIL testing offers:

• Modularity: Individual software components can be tested in isolation.
• Flexibility: Architectural changes can be quickly simulated and evaluated.
• Reusability: Models and test scenarios can be reused from SIL to HIL, where up to 80% of tests can be executed before the first physical ECU exists.
• Virtualization support: Enables testing of containerized applications and service-oriented architectures.

Integration into the Development Workflow: From Code to Feedback in Seconds

One of the key strengths of SIL testing lies in its seamless integration into modern development pipelines. With a powerful API, the entire process—from creating a virtual ECU (VECU) to executing automated tests—can be fully scripted and embedded into existing toolchains.

This means developers can trigger tests directly from their development environments or any CI/CT system. Artefacts generated from source code are automatically built, deployed, and tested—providing instant feedback on whether the implementation behaves as expected. This feedback loop can be part of a pull request, ensuring that every code change is validated before integration.

Even more compelling, OEMs can extend this approach to their supplier networks. Whenever a supplier submits an update, it can be uploaded as an artefact to the cloud and automatically tested within the full virtual vehicle context. This cloud-based validation workflow enables scalable, distributed testing across organizational boundaries—without requiring physical infrastructure or manual coordination.

The ability to run full-vehicle simulations in the cloud also opens the door to on-demand compute scaling, remote collaboration, and continuous integration across global teams. These capabilities are essential for modern development organizations looking to accelerate innovation while maintaining quality and compliance.

SIL Across the Development Lifecycle

While Software-in-the-Loop testing is often associated with early-stage development, its benefits extend across the entire lifecycle of vehicle software. With dSPACE’s SIL solutions, teams can:

• Validate software updates continuously, even after SOP, by integrating SIL into over-the-air (OTA) update pipelines.
• Support variant management, by testing multiple configurations and feature sets in parallel.
• Perform integration testing, by combining multiple VECUs and FMUs into a full system simulation.
• Enable long-term regression testing, ensuring that new features do not break existing functionality.

This lifecycle coverage is especially valuable in agile development environments, where software is delivered incrementally and must be validated continuously. With VEOS and its cloud-native capabilities, these tests can be executed at scale on-demand, across teams, and without hardware bottlenecks.

System-Level Integration with VEOS: Beyond Function Testing

While SIL testing is often associated with function-level validation, the dSPACE VEOS platform goes far beyond that. It enables system-level integration by supporting a wide range of abstraction levels. The abstraction level of a V-ECU provides information about its development status. When it comes to simulation, the following applies: The further the development of the V-ECU progresses, the more details have to be taken into account.

• Level 0 and level 1: In the early phases of development, the focus is on validating individual application components. The exact type of signal transmission between V-ECUs is secondary and is usually not yet fully specified.
• From level 2: Bus communication and the integration of the V-ECU into an overall simulation are becoming increasingly important. From here, basic software for bus communication must be integrated into the V-ECU. For easier integration and faster creation of the V-ECU, simplified basic software that only includes the communication (COM) module is usually used in earlier development phases.
• Level 3: These V-ECUs come very close to the real ECU and ideally only differ in terms of the hardware-dependent driver modules. All basic software located above these modules is part of the test object here and is therefore fully integrated into the V-ECU.

This layered approach allows developers and integrators to select the right level of fidelity for their use case, and to gradually evolve their virtual test environment as the software matures. VEOS supports all these levels and enables their combination in mixed configurations, ensuring flexibility and scalability throughout the development lifecycle.

VEOS is designed to be open and interoperable. It supports integration with third-party simulation and testing platforms, making it possible to build hybrid environments that combine dSPACE tools with external solutions. Whether you’re working with proprietary models, open standards, or commercial software, VEOS provides the flexibility to bring everything together in one cohesive simulation.

VEOS also supports cloud-native deployment models, making it possible to run simulations and tests in scalable cloud environments. This enables organizations to shift from local, hardware-bound setups to flexible, cloud-based validation platforms that support remote access, elastic compute, and global collaboration.

This openness is a key differentiator: it allows OEMs and suppliers to collaborate across tool boundaries, validate across domains, and scale testing across platforms—without being locked into a single ecosystem.

Open Standards and Toolchain Compatibility

dSPACE SIL solutions are built to integrate seamlessly into heterogeneous toolchains. VEOS supports industry standards such as:

• FMI (Functional Mock-up Interface) for model exchange and co-simulation.
• ASAM XIL for standardized test automation.
• AUTOSAR Classic and Adaptive for ECU software integration.

This standards-based approach ensures compatibility with third-party tools and allows customers to leverage existing investments in modeling, testing, and automation infrastructure.

Scalable Deployment: From Desktop to Cloud

One of the key differentiators of the dSPACE SIL ecosystem is its scalable deployment model. Whether running locally on a developer’s workstation or in a high-performance cloud environment, VEOS adapts to the needs of the project and organization.

• Local execution is ideal for debugging, and interactive development.
• Cloud-based execution enables large-scale regression testing, parallel scenario validation, and global collaboration.

This flexibility allows teams to start small and scale up as needed—without changing tools or workflows. Combined with containerization and orchestration support, VEOS can be integrated into enterprise-grade infrastructures, supporting DevOps practices and continuous validation pipelines.

By bridging the gap between desktop simulation and cloud-native testing, dSPACE empowers organizations to build resilient, scalable, and future-proof validation environments—ready for the demands of next-generation vehicle development.

Conclusion: Virtual Validation as a Key to Scalable, Collaborative Development

Software-in-the-Loop testing is more than just a tool—it’s a strategic enabler for electromobility. It allows for faster innovation, higher quality, and lower costs. Especially for battery electric vehicles and new E/E architectures, SIL testing is an essential part of modern development workflows.

With VEOS, dSPACE offers a powerful, open, and scalable platform that supports full system integration, cross-tool collaboration, and cloud-based validation pipelines—empowering developers and organizations to shape the future of mobility together.

dSPACE empowers developers worldwide to unlock these benefits—with powerful tools, deep expertise, and a clear focus on the future of mobility.