Military Embedded Systems

SOSA Technical Standard will benefit systems of all kinds


February 05, 2021

Andrew McCoubrey


SOSA Technical Standard will benefit systems of all kinds
Figure 1 | Curtiss-Wright VPX3-687, a 10G/40G backplane Ethernet switch now available in a SOSA-aligned configuration.

The standards currently being defined by the Sensor Open Systems Architecture (SOSA) Consortium will deliver many clear benefits to system integrators designing embedded sensor-processing systems. The SOSA Technical Standard will define common pinouts that foster and ease interoperability. Greater system flexibility will come from the ability to place a variety of module types into the same system slot, while convergence on common interconnect technologies (such as backplane Ethernet) will ease the integration of modular systems.

Integrators will benefit from having greater choice – even if only some of the cards in the chassis are aligned to the SOSA Technical Standard. Systems that require specialized cards not defined in the SOSA Technical Standard (SOSA Snapshot 3 is currently available to the public at can use those products alongside SOSA cards, thereby benefiting from the economic and technical benefits of standardization on the slots that are aligned to the standard.

The benefits of the SOSA Technical Standard go far beyond its standardized pinout. The reliability of systems deployed in harsh conditions will be improved by its use of the ANSI/VITA 47 standard, which defines requirements for environments, design and construction, safety, and quality. The SOSA Technical Standard also provides a novel approach to serial console ports (using 3.3 V rather than RS-232 levels), making it easier to multiplex ports from several cards onto a single physical interface outside the box. This standard also standardizes functionality required from Intelligent Platform Management Interface (IPMI). While IPMI has long be used to provide basic monitoring of card temperatures, voltages, and various vendor-specific readings, SOSA requires support for VITA 46.11 with HOST Tier 2 extensions to ensure all cards provide a consistent set of sensor monitoring and management commands.

What the SOSA Technical Standard isn’t, though, is a panacea. System integrators will still need to ensure that vendors provide more than just compliance against the technical specification. While the standard will help drive interoperability and commonality, modular products are not becoming a commodity. Different products can deliver different functionality and levels of performance; not all vendors are equal. Interoperability only gets you part way home. Capabilities that support configuration management and mitigate obsolescence, processes that ensure the integrity of the component supply chain, and conformance to quality management systems such as ISO 900x, will remain critical differences between vendors of SOSA-aligned boards.

Because of its origins as a standard for sensor-processing systems (the first “S” in the acronym = “sensor"), the SOSA Technical Standard may not meet the needs of all modular systems. Mission systems that connect to a variety of devices and buses throughout a platform, for example, may still need types of cards that are not defined by the standard. While the SOSA Technical Standard does define backplane Ethernet switches ideal for connecting between processing elements within a chassis, a media conversion card (or a different switch entirely) will be needed if your system needs 10 ports of 1000BASE-T Ethernet to connect to cameras, radios, crew stations, or sensor-processing systems.

The good news is that systems can support a mix of SOSA-aligned processing and mission processing. Imagine a 6-slot mission system: Three slots can host a SOSA-aligned processor card, while the other three can host 1553, storage, and an Ethernet switch that aren’t designed to align with SOSA. The beauty of the SOSA Technical Standard is that its benefits can flow to every type of system, enabling a system designer to take advantage of its ecosystem even if they aren’t designing or deploying a SOSA-aligned sensor-­processing system.

Another concern for some integrators will be that the SOSA Technical Standard and its ecosystem are new. Fortunately, not all SOSA-aligned board products will be brand new, from-the-ground-up designs. Some vendors will offer variants of proven and popular cards. The availability of widely deployed solutions in a SOSA-aligned variant will eliminate the need for designers to make a tradeoff between using a SOSA-aligned module and mature technologies.

An example that will be available in both traditional and SOSA-aligned versions is Curtiss-Wright’s VPX3-687 backplane Ethernet switch, a 3U OpenVPX module with switching throughput up to 320 Gbits/sec and full-line-rate forwarding on up to 32 x 10 GbE/8 x 40 GbE interfaces. (Figure 1.) The SOSA version, which aligns with the SLT-3-SWH-6F1U7U-14.4.14 profile, is orderable now (early 2021), meaning that designers can start developing SOSA-aligned solutions now using a proven product that will be available later in a SOSA-aligned variant.

Andrew McCoubrey is the product marketing manager, switching and routing solutions, for Curtiss-Wright Defense Solutions.

Curtiss-Wright Defense Solutions

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