#openvpx

Chassis Management Defined

VITA 46.11 defines a chassis management architecture for OpenVPX that provides automated oversight and administration tools, which serve to provide better insights into a system’s health. As more intelligent monitoring functions are implemented into OpenVPX applications, the need to properly enable smooth system operation and resource management becomes more important.

A Chassis Manager has three primary functions to help keep systems healthy, manage system power and ensure proper cooling (Figure 1):

Resource management: discover all intelligent FRUs (IPMCs), boards and sensors in the chassis as well as any other components that support VITA 46.11

Event monitoring: provide a history of all events on the sensors for each FRU, such as an over-temperature or an under-voltage condition

Diagnostics and response: flag any abnormal or failed sensors or fans as well as clogged filters; adjust fan speed for irregular temperature conditions; report or shut down due to over-/under-voltage/current conditions

Other components of a chassis management system include the IMPI, or Intelligent Platform Management Interface, which manages and monitors system capabilities independently of the host system, and the corresponding IPMB, or Intelligent Management Interface Bus that facilitates system management and IMPC, Intelligent Management Interface Controller designed to help manage the system.

Layers of Management Functionality

Layers of Management Functionality VITA 46.11 also defines two tiers of functionality for the chassis manager and the IPMC to enable implementation flexibility. Tier 1 is the easiest to implement, while Tier 2 provides the highest functionality (Tier 3 is in development).

Chassis Manager Baseline Tier-1:

Maintain an FRU population table containing information for each FRU in the chassis, whether a plug-in module or another type of chassis FRU

Bridge between the System Manager logical layer and the IPMC logical layer

Maintain IPMC state information for each IPMC in the chassis

Chassis Manager Advanced Tier-2:

Tier 2 is a superset of Tier 1, but adds functionality and complexity in capabilities

Support the discovery of each FRU in the chassis

Support management of chassis infrastructure

Participate in event generation and reception

Support event logging

Support dynamic sensor devices

Support FRU recovery, including FRU reset and power cycling

FRU payload control – power, reset, graceful reboot, and initiating diagnostics

IPMC Basic Tier-1:

Responsibility for system IPMB start-up and fault handling

Supporting the discovery of the FRU it controls

Supporting access to the management information for the FRU it controls

IPMC Advanced Tier-2:

Also a subset of Tier 1, adding more capabilities

Participate in event generation and reception

Support dynamic sensor device

The Impacts to on OpenVPX Systems

Chassis managers – as defined in VITA 46.11 – now enable the system designer to find faults before any defects negatively impact the individual board or the entire system; correctly implemented, the chassis manager also can help maintain power levels and reduce overall downtime. Monitoring the health, power and cooling of VPX boards used across military applications, including radar, electronic warfare (EW), communications, sensor processing, etc., is just as important as keeping an eye on the performance and capability of the end system.

When Tier 3 is available, it will also provide reconfigurability for faster redeployment and health monitoring in the event that elements of the chassis start to fail. This becomes even more important as open standards initiatives – such as the Sensor Open Systems Architecture (SOSA) Technical Standard – are making chassis managers a requirement.

Positive Effects from the SOSA Initiative

During development of the SOSA Technical Standard, Consortium members worked together to introduce VITA 46.11 to power supply modules. This was because SOSA requires monitoring of the power supplies for reporting and control. The result is that chassis managers now have the capability to monitor power supplies within a chassis thanks to contributions from the Sensor Open Systems Architecture (SOSA) Consortium to the VITA 62 standard. So, although SOSA was pushing for power supplies to support 46.11, VITA 62.0 is where this is actually implemented.

In addition to power supplies now accepting commands from the chassis manager, a smart board is contained within VPX power supplies, so the PSU can interface with the chassis manager via the IPMB, providing even better oversight of system resources.

Want to learn more about VPX chassis management and how it relates to SOSA initiatives? Download the white paper ”Chassis Managers: Monitoring Chassis Health and OpenVPX and SOSA Aligned Boards in Military Systems“

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Elma Electronic has enhanced its line of SOSA aligned backplanes to include a 7-slot 3U OpenVPX model that further supports the DOD’s Modular Open Systems Approach (MOSA) mandate.

Complete with six VITA 65 slots and one VITA 62 PSU slot, the new backplane helps facilitate the development of a common architecture across critical C5ISR and EW systems. Specific application functions include mission, weapons or navigation control, surveillance, as well as threat detection and processes or environmental monitoring.

For CMOSS and RF applications, the new backplane features three payload slots and PNT support across all slots. All control and data plane links are designed for 25 Gbps data rates for high-speed signaling on all data paths and support dual domain Ethernet up to 100GBASE-KR4.

The full featured backplane offers cutting edge VITA 67.3 interconnect technology, with VITA 66 and VITA 67 connector modules installed in the backplane apertures upon request.

Support for a number of critical features including a radial slot card for precision timing and synchronization, support for VITA 48.2 2-Level Maintenance (2LM) and VITA 62 PSU isolation fins for high altitude applications are available on this 6+1 backplane.

At Elma, we’re often asked: “I’ve got a VPX chassis and a set of VPX boards…can I just plug them in and power it up?”

‍ The short answer: No. ‍

The longer answer: It depends — but if you don’t verify compatibility first, you may be risking expensive damage. ‍

While VPX (VITA 46) and OpenVPX (VIITA 65) standardize board and system level interoperability, when it comes to real-world implementation, there’s still a set of checks and balances to apply to system development. ‍

With nearly four decades of experience supporting embedded computing platforms for defense, aerospace, and rugged industrial applications, we’ve seen just about every integration scenario — good, bad, and costly. ‍

That’s why this installation of our Elma TIPS blog series focuses on the very first step in VPX system integration, profile compatibility, to hone in on some best practices and avoid headaches down the line.

The Importance of Starting Right

A common issue that still surprises us? Customers who receive a VPX chassis simply plug in boards without checking the profiles, and hope for the best. This kind of trial-and-error approach might work with consumer tech — but in VPX and SOSA® aligned* systems, mismatched profiles can result in damaged hardware or even catastrophic failure.

Module and Slot Profiles — The Foundation of a Successful Build

Every VPX module — also known as a plug-in card (PIC) — is built to a module profile defined by the VITA 65 OpenVPX specification. These profiles define:

• The pinout of the VPX connectors • Supported protocols (e.g., PCIe, Ethernet, Serial RapidIO) • Power distribution and grounding • Optional user-defined I/O zones

Likewise, each backplane slot has its own slot profile (Figure 1), specifying the types of signals it supports and how it connects to other slots in the system.‍

Figure 1. Each backplane has a defined slot profile to indicate the signals it supports and how it connects within the system.

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Figure 2: The backplane topology diagram is important in system design to facilitate integration and debugging

Mismatched your PCIe lanes with Ethernet? They can’t communicate, and you might even damage driver and receiver circuits.

Mismatched the ground planes? You could permanently damage a $25,000 (or more) card before you even start your software development.

Your Integration Checklist

To avoid costly mistakes, follow this simple checklist when starting VPX system integration:

‍1. Know Your Module Profiles Review each board’s datasheet or user manual. Reputable module vendors (and SOSA aligned ones in particular) will list the supported module profiles, often referencing the exact VITA 65 designation.

Figure 3: Examples of compatible and incompatible sets of Module and Slot Profiles

2. Understand Your Backplane Make sure you also have detailed datasheets for the backplane that, at a minimum, includes: - Slot-by-slot profile information - Topology diagrams showing how slots are interconnected - Supported signaling standards per slot

3. Consult the OpenVPX Specification For instances where not all the information is available or a bit more clarity is needed, the VITA 65 standard is the definitive reference for profile definitions. It details all approved combinations, interface assignments, and mechanical constraints.

4. Ask for Help Integration is rarely one-size-fits-all. At Elma, we’re accustomed to supporting customers at all stages of the game: during pre-development discussions, design reviews and post-deployment troubleshooting. If you’re not sure whether a board will work in a given slot, just ask us.

Common Pitfalls We See (So You Can Avoid Them) • Skipping documentation — Don’t assume a board labeled “VPX” will work in any VPX slot. It’s not like USB, where it’s almost always safe to plug a device in. • Overlooking ground and utility pins — These are just as critical as signal lines, especially in high-speed systems. • Mixing SOSA aligned and non-aligned boards without proper planning — This can work, but only with proper analysis of backplane topology and signal compatibility.

Integration is a Process, not a Guess Matching profiles isn’t optional, it’s fundamental. Get that right, and the rest of your system integration gets much smoother. More than just offering a wide range of backplanes, chassis, and integration services aligned to the SOSA Technical Standard and VPX ecosystem, at Elma, we consider it part of our job to help our customers succeed — from identifying the basics to handling complex system integration. For more TIPS and insights on embedded system development, check out our other blogs.

*Note: the SOSA standard makes use of a specific set of VPX profiles for its hardware elements.

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