Perhaps surprisingly, one of the many benefits that the SOSA™ Technical Standard offers involve development chassis.
Development chassis are nothing new in embedded computing; they date back to the earliest days of VME, and labs often have development chassis for board design testing and bring up, subsystem testing, or software development and integration. Like deployable systems, development chassis have evolved alongside new industry opens standards.
This is noteworthy because when designing with VPX, a chassis with a single-slot or multi-slot power-and-ground backplane — where all other signals are running straight through to rear transition module (RTM) connectors — can be handy for working with a single board, or multiple boards connected through the RTM boards. However, before the introduction of the SOSA Technical Standard, it was difficult to purchase a commercial off-the-shelf (COTS), multi-slot backplane for a development chassis that supported high-speed slot-to-slot links, due to the varied pin mappings that different vendors chose for their plug-in card products.
The SOSA Technical Standard changed that. By limiting the number of slot profiles and defining specific protocols supported on the various communications planes, companies can now offer COTS backplanes that align to the technical standard and can support similarly SOSA aligned plug-in cards from different suppliers. This means that developers can now purchase off-the-shelf development chassis that permit true multi-board subsystem, or even full system, development.
Open Standards Accelerate System Development
In addition to freeing developers and integrators from the limitations of RTMs and external cabling to link boards in a backplane as well as the need for custom backplanes, SOSA aligned COTS backplanes in development chassis provide several other interesting advantages:
• Subsystem or complete system development: In the past, one usually had to jump from a one- or two-board development platform with limited communications links directly to a target custom backplane, often in the target deployable chassis. Using development platforms based on SOSA, such as Elma’s CompacFrame chassis with SOSA backplanes, one can build up a system component-by-component and validate design elements prior to committing to a target deployable platform design. The fact that development hardware often includes VITA 46.11 chassis management hardware means that even the chassis management itself, which is a function distributed across multiple components in a system, can be brought up and debugged prior to moving to deployable hardware.
• Signal integrity testing: SOSA aligned COTS backplanes in a cost-effective development chassis provide an ideal environment for signal integrity testing of new board designs. By plugging a target-test board into various slots, one can measure the quality of high-speed signals nearer or farther from a board under development using a COTS backplane with known signal characteristics.
• Pre-deployment field testing: It’s now possible to obtain semi-deployable development chassis based on COTS components, such as Elma’s ATR-3600S that uses the same backplanes as lab-grade development chassis. These types of platforms allow for rapid field testing of subsystems or complete prototype systems prior to committing to a production-deployable design.
Development hardware can also be shared between projects, or inherited by subsequent projects, even though they may have different — and sometimes completely dissimilar — board-level content. This saves not only on lab budget, but the time to order and receive all new hardware for a new development project. Should a backplane from a previous project not fit the architectural needs of a new project, there is a good chance that another COTS backplane could, simplifying development platform upgrades to new architectures or slot counts.
Enhanced Design Outcomes in Chassis Development
Sometimes, the unintended consequences of our actions benefit us in ways that we never expected. The advantages of SOSA to deployed platforms, such as ease of integration, enabling future technology insertions and breaking vendor lock, were utmost on the minds of the framers of the technical standard.
However, looking back we can now see a shift in how development platforms are designed and offered by embedded manufacturers as well as how they are used by our integrator customer base. That shift is making it easier and less expensive to perform the development stages of a deployable system project and put solutions into the hands of the warfighter faster than ever before.
