Powerstar UPS - ps1503-4
      Data Multiplex System
    The Rockwell International Autonetics Marine and Aircraft System Division (AM&ASD), now Boeing, began developing general purpose digital data bus systems for naval applications in 1970.  The first such system is the Data Multiplex System (DMS) AN/USQ-82(V), a linear, coaxial, five-way redundant digital data bus designed specifically to be compatible with a large number of standard US Navy signal types, discrete, logic level, supervised discrete, analog, synchro, serial digital, and parallel digital.  The goal of DMS was to allow the rapid incorporation of data bus technology into Navy ships, and therefore required that modifications of user equipment be minimized or avoided entirely.

    DMS achieved this goal by including a large menu of options for user device interfaces.  The DMS terminals and the interface modules can be configured for a wide variety of options which address interface signal details as well as various protocols for digital devices.  DMS also incorporates a number of features to promote a high level of survivability, to ensure that it is adequate to support critical shipboard systems.  Finally, DMS is built to military specifications, including shock, vibration, humidity, electromagnetic emissivity, electromagnetic susceptibility, and many more.

    In 1984 DMS completed US Navy Operational Evaluation (OPEVAL), and was incorporated into the design of the Arleigh Burke (DDG 51) class destroyers and, in a smaller application, in the Wasp (LHD 1) class amphibious assault ships.  DDG 51 is currently operating with machinery control, damage control, steering, navigation, alarm and indication, and parts of the AEGIS combat system communicating over DMS.  LHD 1 uses DMS for the distribution of navigation, wind, and radar antenna bearing data.
      Fiber Optic Data Multiplex System (FODMS)
    In 1984 the US Navy began investigating commercial data bus standards to see if any might be used or might be adapted for navy use.  The Survivable Adaptable Fiber Optic Embedded Network (SAFENET) committee was formed, surveyed various topologies, and decided to adopt the American National Standards Institute (ANSI) X3T9.5 Fiber Distributed Data Interface (FDDI) token ring architecture.  SAFENET mandates, in addition to the FDDI medium, that a SAFENET-compliant system must be designed to certain physical requirements to promote durability and survivability, and must support certain protocols and services.

    To comply with SAFENET, while still providing the compatibility with existing US Navy users systems, work began on the Fiber Optic Data Multiplex System (FODMS) in 1988.  FODMS is a FDDI-based data bus transparent to any current application of DMS.  FODMS is designed to operate in a SAFENET environment.  FODMS is based on two (2), redundant packet-switched, dual counter-rotating ring FDDI networks, which are used to interconnect the nodes, or Input Output Units (IOU's).  The main bus medium conforms with the physical requirements set forth in the SAFENET Standard of 20 December 1991.

    The FODMS currently resides on the DDG 51 Flight IIA Class Destroyer ships.  The FODMS systems currently facilitates the following users; analog navigation data to indicators and synchros for combat systems, digital navigation data to combat systems, interior communication (IC) alarms and indicators, integrated survivability management system, machinery control system, and steering control system.

    The FODMS reduces cost, increases performance, expandability, survivability (self healing network rings), and simplifies the shipboard installation.  It also reduces Life Cycle Cost (LCC) for procurement, operational and support of the system.  The maintainability of FODMS has improved over its predecessor.  FODMS introduces true multicast and broadcast services, which improve the distribution of digital navigation data to combat systems.
      Gigabit Ethernet Data Multiplex System (GEDMS)
    The GEDMS system will be a technology refresh to the Fiber Optic Data Multiplex System (FODMS), which is currently being installed on the Arleigh Burke DDG51 Flight II Class of destroyer ships (DDG 79 – 110).  The GEDMS system will increase the overall networking bandwidth by replacing the Fiber Distributed Data Interface (FDDI) backbone associated with the FODMS system and installing a Gigabit Ethernet backbone.  The GEDMS system provides a means to transfer data, command or status messages between various types of user source and user sink devices.  For purposes of survivability, the GEDMS system will incorporate a Mesh Topology over two independent network backbones.  Each network will utilize Backbone Switch Enclosures (BSEs) for connection to both network and user links via the fiber optic cable plant.  The network links (Switch-Switch) will establish the mesh topology backbone associated with GEDMS.  The user links (Switch-User) will provide the connection of the Input/Output Units (IOUs).