In the early development phase, functional tests can be performed on a Windows desktop PC (Model-in-the-Loop – MiL). COSYM furthermore supports the integration of models from a variety of sources, like MATLAB®/Simulink®, C code, or the Functional Mock-up Interface 2.0 (e.g. physical models from Dymola or GT-SUITE).

Connection versatility: COSYM integrates artifacts, models, and bus configurations to be tested for simulations and experiments on a variety of platforms.

COSYM can be used for both closed-loop and open-loop testing, and it is possible to simulate discrete-time as well as continuous-time systems. COSYM specifically uses open standards (e.g. ASAM XiL, FMI, and CDF). Thus, the ASAM XiL interface, for instance, facilitates the connection of a test automation software solution. If the ASAM XiL standard is used, existing test libraries can then be utilized in COSYM.

More cost-effective and time-saving SiL tests

When using virtual ECUs, COSYM can also be deployed for Software-in-the-Loop (SiL) tests. In this context, such ECUs can be connected to a virtual CAN/CAN FD bus. The COSYM architecture ensures that the communication via buses like CAN is simulated in sync with the overall system.

The use of COSYM for SiL tests provides significant benefits:

  • More cost-effective and less time-consuming
  • Enables the integration and testing of virtual ECUs that are generated with, for instance, ETAS ISOLAR-EVE
  • SiL tests can be reused seamlessly during HiL testing
  • Communication between virtual ECUs can be simulated realistically and used for tests  

COSYM for HiL use

COSYM can also be used for Hardware-in-the-Loop, predominantly for testing ECUs under real-time conditions with the help of the LABCAR product family (LABCAR system). In this case, models, parameters, test scripts, etc. already created for MiL and SiL use can be reused with the same user interface.  

The graphical user interface (GUI) of ETAS COSYM is intuitive to use. COSYM allows a wide range of different artifacts to be integrated into a library. These artifacts can be combined into a complete system via virtual buses or signals, which makes it possible to model the E/E architecture of a vehicle in the simulation.

In addition, COSYM permits scheduling to be freely defined in the simulation. After creating the overall configuration, either the RT PC (Hardware-in-the-Loop system) or the local Windows PC (Model-in-the-Loop/Software-in-the-Loop) can be selected as the executing platform.

All functions that can be accessed using the graphical user interface can also be implemented using the COSYM REST-API and dedicated program code. This enables, among other things, seamless integration in customer-specific workflows (continuous integration).

The COSYM EE experiment environment is used to control the simulations and experiments. This separation of the integration platform and experiment environment offers clear control concepts for the respective user group that are tailor-made for the user group’s tasks.

When it comes to the MiL/SiL use case, the simulation can be controlled based on scripts via a Python interface as an alternative to using COSYM EE.

Controlling simulations – with the COSYM EE experiment environment

HiL use case

In the HiL (Hardware-in-the-Loop) use case, a real ECU can be connected to an ECU environment simulated on a LABCAR RTPC via physical I/O and bus interfaces with connected real or simulated loads. On HiL test benches, simulation scenarios can be used that are identical to or different from those in MiL/SiL environments. In typical use cases, automotive control units, such as engine control units or battery management systems, are tested and validated.

To implement a HiL use case with real prototype ECUs or production ECUs, a LABCAR HiL system is needed that is supported by COSYM. The integration and experimentation platform COSYM provides the functionalities necessary for the test project, such as the integration and configuration of C code modules as well as FMU and MATLAB®/Simulink® models and the simulation of bus systems (rest-bus simulation). COSYM also makes it possible to implement the overall configuration of the test project and provides the environment for the real-time experiment.

ECUs are tested under real-time conditions with the help of modules from the LABCAR hardware product family (LABCAR HiL system). To simulate the environment, it is possible to use, among other things, plant simulations of the LABCAR models.

In addition to testing individual ECUs, HiL test benches can (depending on their configuration) also be used for the validation of domain ECU networks (e.g. the powertrain) as well as ECU networks for the entire vehicle.

MiL/SiL use case

COSYM EE can be used to control the simulation on a Windows PC – in the same way as for the HiL use case. Using the COSYM user interface, it is possible to integrate virtual ECUs in different abstraction stages – starting from the software model (coming from e.g. MATLAB®/SIMULINK) to nearly production-ready ECU software (using a C/C++ interface). It is likewise possible to integrate virtual ECUs in COSYM that have been created with ETAS ISOLAR-EVE, that originate from third-party vendors, and that have been created using in-house solutions.

If, like ETAS ISOLAR-EVE, the ECU software is equipped with an interface for automotive bus systems, the communication between multiple virtual ECUs can be simulated realistically for the CAN and CAN FD standards.

Another big advantage is the significantly reduced computing time for real-time models achievable in ideal circumstances. In addition to this, it is of course also possible to calculate computationally intensive non-real-time models.

COSYM base products


COSYM HiL is the integration and experimentation platform for testing ECUs (Hardware-in-the-Loop). It enables the integration and configuration of C code, FMU, and MATLAB®/Simulink® models.


COSYM MiL SiL enables the integration and configuration of C code, FMU, and MATLAB®/Simulink® models for simulation on a Windows PC. 

COSYM add-ons


COSYM HiL CCI (Calibration Connector for INCA) enables INCA to provide model-synchronous measurement and calibration access to the ECU.


COSYM MiL SiL EE is an experiment environment. It makes it possible to perform simulations and experiments based on the integrated model.


COSYM MiL SiL PA helps with the parameterization of models by enabling a self-definable arrangement and grouping of parameters across the models of the system. This allows application-specific views to be generated that make parameterization easier.


COSYM MiL SiL TC SIMULINK enables co-simulation between models in COSYM and models in MATLAB®/Simulink®. No generated code is required from MATLAB®/Simulink®, since the MATLAB®/Simulink® models are executed in their original environment.


COSYM MiL SiL VNET (Virtual Networks) enables the simulation of a CAN bus.


COSYM NIC (Network Integration CAN) is used for configuring and carrying out tests that require a rest-bus simulation with CAN.


COSYM NIF (Network Integration FlexRay) is used for configuring and carrying out tests that require a rest-bus simulation with FlexRay.


COSYM NIL (Network Integration LIN) is used for configuring and carrying out tests that require a rest-bus simulation with LIN.


COSYM NAE (Network Integration Automotive Ethernet) is used for configuring and carrying out tests that require a rest-bus simulation with Automotive Ethernet.


COSYM HiL RTC (Real-Time Execution Connector) is used to configure and connect LABCAR hardware together with the real-time target.

Designed for the cloud

Proof of compliance with new emission standards (Real Driving Emissions, RDE) or the development of autonomous driving functions require the intensive use of virtual road tests. These can only be implemented within an acceptable time frame by using massively parallel computation in the cloud. COSYM is the simulation platform of the future. Since COSYM is based on a scalable and modular architecture, it ensures customers are optimally prepared for testing and working in the cloud.