Triakis VSIL: A single, unified test environment that takes you all the way to certified, zero-defect software without the expense of development & test support hardware.

Virtual System Integration Lab (VSIL) Cost-Saving Benefit

100% virtual, total environment simulation.
Accepted by the FAA and the EASA as a complete software qualification environment to DO-178B levels A to E. No hardware required!
Proven ability to consistently produce zero-defect avionics software.
Provides three levels of development support:
·         System executable specifications
·         Pseudo-processor w/RTOS emulation
·         Instruction set emulation
Maintains flow-down verification test compatibility with all three.
System-level, and software-level verification test consistency method validated by NASA software assurance research
Allows you to run MCDC- tracking instrumented code with no timing penalty (runs as though it were uninstrumented).
Virtual system extends as far as you need to verify target avionics system and software behavior in response to external stimuli and other influences.
Provides full range of signal types for realistic environment modeling:
Digital · Analog · Magnetic · Mechanical · Hydraulic · Pneumatic
Electromagnetic · Inertial · Frictional · Gravitational · Optical · etc.
Variable fidelity of all VSIL parts – pay for only the fidelity you need.
All parts within entire system environment can incorporate failure modes that may be selectively manifested under test control.
Intuitive verification testing through software scripting environment.
“One-click” full regression test to re-verify all code following changes.
Used on multiple NASA software assurance research projects.


Because of the part-oriented nature of the simulators we use, the cost of creating a simulator for a given project will vary in proportion to the number and complexity of new parts that must be created.  Many new embedded designs reuse proven subsystem designs from prior projects so the cost of developing simulators diminishes to some extent with successive applications. 

To enhance the use of the VSIL as a test vehicle, you will receive simulations of standard laboratory test equipment such as oscilloscopes, signal generators, and the functional capability of microprocessor emulators.  The VSIL is an ideal environment for gathering dynamic software metrics without instrumenting either the target operating system or the software.  Code path coverage, MCDC reports, throughput analysis, timing analysis, and many other helpful reports are readily produced in this environment. 

In addition to our NASA research efforts, this tool has been used to create VSILs for software verification on more than two-dozen avionics projects over the past decade.  During that time it has benefited from numerous refinements and enhancements culminating in the capabilities described herein.  This well-proven tool, scalable to any size system, has been used for verification of software in single and dual-redundant avionics systems ranging in DO-178B criticality levels from A to D.  It has also been used for verification of embedded digital signal processor (DSP) software implementing Kalman filter algorithms. 

Over the years Triakis’ library of parts has grown to include instruction-set level simulations of many of the popular microprocessors in use today such as the MPC555, MPC750, RAD6000, MC68000, MC68332, DSP56005, DSP56302, DSP56309, I80196, I8051, I8096, I8097, I8798, et al.  Our library is filled with numerous additional peripheral and “glue” parts, as well as a host of actuators and sensors that have been used to create various VSILs.  In support of connecting the various system elements in our avionics VSILs, we have also simulated many different data buses and protocols e.g.: ARINC 419, ARINC 739, MIL-STD-1553, TTP, ASCB, CSDB, AFDX, Ethernet, SPI, PCI, etc.

With the sizable number of parts available to choose from, typically, the time and expense required to create new VSILs is relatively low.  The benefit of using a VSIL for embedded systems & software development increases with project size, with system complexity, and with geographic diversity of organizations and personnel contributing to the project.

Developing & Verifying Software with a Triakis VSIL

Developing software on a typical embedded project requires you to purchase a variety of software tools and hardware test equipment. These include microprocessor development boards, emulators, peripheral system simulators, and configurable test beds (automatic test equipment, system integration labs, etc.) in quantities commensurate with the size of the project. This equipment is expensive, which limits the amount you can buy and creates resource contention problems at critical phases of software development and testing. Further, due to the nature of this federated component approach, significant programmer and tester efficiency is lost due to inconsistencies in component test setup, operation, and synchronization. This environment must be reconfigured for each new software test, making configuration management and regression testing a laborious process. Thankfully, there is a better and easier way to do this.

Imagine how much more efficient your software teams could be by using a completely virtual, unified development and verification environment. Triakis models all of the peripheral hardware components necessary to develop and verify avionics software in one environment, to the most demanding standards required by the FAA and EASA. Triakis creates your custom virtual system integration laboratory (VSIL) from its sizeable part library and from components unique to your project. Your object-oriented VSIL provides each software team member with a complete development and test environment at their desk with the following features:

  • Runs on Windows-based PCs, connected to your preferred embedded development environment through the COM channel interface.
  • Compiled object code loads directly into VSIL virtual target memory.
  • VSIL can run software source code before a microprocessor is selected and hardware is fully designed. Software source compiles with the VSIL using Visual Studio and runs in a pseudo-processor part, with your preferred real-time operating system interface.
  • All tests are requirements-based and environment-driven in a logical, object-oriented manner delivering excellent test realism. For example:
    • Landing_Gear_Lever -> Move_UP  // Move to UP position
    • Delay x milliseconds  // As requirement allows for action initiation
    • Landing_Gear_Main -> Get_gear_state  // Verify gear is retracting
  • All VSIL parts can implement failure and degraded operating modes that may be manifested as required under test control.
  • Peripheral avionics subsystems, such as Multifunction Control-Display Units (MCDUs) and Central Maintenance Computers (CMC), can be user operated or driven and interrogated under test control.
  • VSIL provides virtual test equipment (oscilloscopes, bus analyzers, signal generators, RTOS task monitors, memory monitors, etc.) configured as desired under test control.
  • All data in the environment is accessible at any time during development and test.
  • When code execution is paused, the entire environment stops and remains synchronized with the target processor while single-stepping through code.
  • Power-up sequence and hold-up timing is modeled for accurate test results.
  • VSIL is compatible with DWARF symbolic debugging standard.
  • VSIL can be configured to run code instrumented with coverage analysis tools, such as LDRA and IBM RTRT, with no timing differences compared to uninstrumented code.
  • Running a single, a group, or a full regression test is equally effortless.
  • The FAA and EASA accept formal software qualification in a Triakis VSIL without testing on hardware—for all DO-178B criticality levels. 
  • Triakis creates the VSIL and provides appropriate DO-178B qualification documentation. Creating completely virtual environment simulators to verify software is our core competency.
  •  Path coverage and other VSIL reports provide valuable progress-tracking metrics.
  • All changes to system and hardware design are implemented in VSIL, maintained under configuration control, and distributed to entire team. Everyone is always working with the latest configuration—no matter how diversely located they are.

Software Sustainment with a VSIL

Sustaining avionics hardware and software following entry into service requires a steady, often substantial investment over their service life. As hardware components age to obsolescence, redesign of functional elements or entire circuit card assemblies may be required to assure continued maintainability. This can have a cascading effect on the need to reconfigure or update test hardware and modify flight and test software in response. Further, the role of sustaining engineering is to investigate and correct anomalous software behavior that may manifest while in service and to develop and verify software to enhance and extend the avionics system capabilities.

Fulfilling this software support role necessitates maintaining the development environment (emulators, breadboards, workstations, associated software applications, etc.) and the test hardware used by the project that produced the target system. Whether you are an avionics manufacturer sustaining your commercial product lines or are charged with maintaining software for a mixed fleet of military avionics, you undoubtedly are on the lookout for assets with real potential to improve your effectiveness in carrying out this daunting mission.

If instead of maintaining a host of federated pieces of development and test hardware, simulators, and applications, imagine having a development environment that:

  • Is 100% virtual and requires no peripheral development or test hardware.
  • Is accepted by the FAA and EASA for total software qualification without test hardware.
  • Runs on Windows-based PC.
  • Can qualify software to any DO-178B criticality level.
  • Runs code instrumented for DO-178B MCDC analysis with no timing impact.
  • Equips every project member with a full development and test environment at their desk.
  • Connects seamlessly with Windows-based embedded software development environments, such as Green Hills Multi, Altium Tasking, and Gnu.
  • Runs uninstrumented flight object code.
  • Has a consistent, logical automated test ability that eases new test development and makes full regression testing a snap
  • Uses virtual parts that are closely correlated to real hardware parts, so that hardware obsolescence redesigns are readily translated into the virtual environment to support software regression testing.
  • Is immune from obsolescence as long as Windows-based PCs are around

Triakis’ 100% virtual system integration lab (VSIL) simulation technology addresses many of the technical challenges and costs of sustaining avionics software. Sustainment engineering is a demanding profession: ask Triakis to make your mission more manageable by creating 100% virtual replacements for your software support hardware.