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Frequently Asked Questions about OpenVPX


General Questions

  1. Why was OpenVPX created in the first place?
    The US Department of Defense and other users are mandating improved implementation of open standards and interoperability. VPX standards have been focused at the board level, but there is also a need for considering system-level requirements to improve interoperability and reduce customization, testing, cost, and risk.  OpenVPX was created to answer this system-level need.

  2. What are the general OpenVPX features?
    • OpenVPX is a defined set of system implementations within VPX
    • Specifies a set of system architectures
    • Uses existing VPX REDI standards and drafts with minimal possible changes
    • Defines multiple planes for Utility, Management, Control, Data and Expansion
    • Defines various sizes of pipes used for serial communication
    • Defines several types of profiles for structure and hierarchy in the standard:
      • slot profile
      • backplane profile
      • module profile
      • development chassis profile
    • Backplane profiles define the backplane topology (types: centralized and distributed switching, and host/slave)
  3.  What is OpenVPX used for?
    OpenVPX is a defined set of system implementations within VPX, defining a set of system architectures and providing a framework for interoperability between modules and backplanes. With OpenVPX, system integrators can more readily architect an application specific system based on compatible OpenVPX profiles for modules, backplanes, and development chassis.

  4. Does OpenVPX replace VPX?
    No. OpenVPX is a system standard for VPX that provides a defined architectural framework for interoperability between OpenVPX products. OpenVPX leverages the VPX dot specs for details such as fabric protocols.

  5. What’s the difference between VPX and OpenVPX?
    OpenVPX builds on VPX dot standards and provides a defined framework for interoperability between OpenVPX products based on compatible OpenVPX profiles for modules, backplanes, and development chassis.

  6. What is an OpenVPX slot profile?
    An OpenVPX slot profile is a physical mapping of Ports onto a given slot’s backplane Connectors. These definitions are often made in terms of Pipes. Unlike Module Profiles, a Slot Profile never specifies protocols for any of the defined Ports. Profile Parameters are used to further describe properties of a Slot Profile.

  7. What is an OpenVPX module profile?
    An OpenVPX module profile is a physical mapping of Ports onto a given Module’s backplane Connectors and protocol mapping(s), as appropriate, to the assigned Port(s). This definition provides a first-order check of operating compatibility between Modules and slots as well as between multiple Modules in a Chassis. Profile Parameters are used to further describe properties of a Module Profile.

  8. What is an OpenVPX backplane profile?
    An OpenVPX backplane profile is a physical definition of a backplane implementation that includes details such as the number and type of slots that are implemented and the topologies used to interconnect them. Ultimately a Backplane Profile is a description of Channels and Buses that interconnect slots and other physical entities in a backplane. Profile Parameters are used to further describe properties of a Backplane Profile.

  9. What is an OpenVPX development chassis profile?
    An OpenVPX development chassis profile is a physical definition of a development chassis implementation that includes details such as the chassis type, slot count, primary power input, module cooling type, backplane profile, and supplied backplane power that are implemented in the development chassis profile.

  10. What are OpenVPX planes used for?
    OpenVPX planes are a physical and logical interconnection path between elements of a system used for the transfer of information between elements. The following Planes are predefined by OpenVPX: Control Plane, Data Plane, Expansion Plane, Management Plane, Utility Plane.

  11. What are OpenVPX pipes used for?
    OpenVPX pipes are a physical aggregation of differential pairs used for a common function that is characterized in terms of the total number of differential pairs. A Pipe is not characterized by the protocol used on it. The following Pipes are predefined by OpenVPX:
    • Ultra Thin Pipe (UTP)
    • Thin Pipe (TP)
    • Fat Pipe (FP)
    • Double Fat Pipe (DFP)
    • Quad Fat Pipe (QFP)
    • Octal Fat Pipe (OFP)
  12. What styles of OpenVPX backplanes are available?
    OpenVPX backplanes are available in lengths between one and twenty-one slots. On most standard backplanes, boards are located on 1.0” centers (i.e. 1.0” pitch), though 0.8” pitch or 0.85” pitch may also be used. Backplanes are available in 3U and 6U form factors. Furthermore, there are many different profiles available for OpenVPX backplanes:
    • Central switch topologies
    • Distributed topologies
    • Root-leaf topologies
  13. Can I get alternate cooling methods for OpenVPX hardware?
    Yes. OpenVPX supports numerous cooling schemes.  These are used mainly in military and aerospace applications where convection cooling cannot be used. These allow heat to conduct through the printed circuit board or through a conduction plate or channels on the module. Expanding wedge locks then transfer the heat out to the chassis through wide slots cut into the metal chassis sidewalls.  Multiple cooling methods are defined in the VITA 48 standards.
    • Standard Air Cooled
    • Air Flow Thru
    • Air Flow-By
    • Conduction Cooling
    • Liquid Cooling
    • Liquid Flow Thru
  14. What are the OpenVPX connector pin assignments?
    OpenVPX connector pin assignments are defined in several slot profiles aimed at different types of slots:
    • Payload slot profiles
    • Switch slot profiles
    • Peripheral slot profiles
  15. Are user defined pins available for I/O signals in OpenVPX?
    Yes. The user I/O pins are defined in the slot profiles.

  16. What power supplies are available on the OpenVPX backplane?
    This is the same as VPX with the exception that OpenVPX currently does not support the 48V power option for 6U modules. OpenVPX also encourages more standardization in the use of the primary power rails but the rails are unchanged from VPX.

  17. Where can I get a copy of the VPX and OpenVPX standards ?
    VPX and OpenVPX are ANSI/VITA approved standards - ANSI/VITA 46 and ANSI/VITA 65. They are available for purchase from VITA, along with several associated standards.

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