INTRODUCTION
For future reference, we encourage you to record the assembly part number and
serial number of your OmniBus product. You may wish to use the space provided
below:
Assembly PN: ________ - ________ - ________
(Board PN) (Core A PN) (Core B PN)
Serial No: __________________
1.3 Avionics Databus Protocols
Avionics databuses interconnect various electronic equipment (navigation, con-
trols, displays, sensors, etc.) on an aircraft, much as a local area network (LAN)
interconnects computers in an office. Data from one device is passed over the
network to other devices that need it. There are a number of military and
commercial avionics databus standards. OmniBus products support the most
common protocols, which are briefly described below:
• MIL-STD-1553 is the protocol for military aircraft and other military and
commercial applications. It is a digital, command-response, time-division
multiplexing databus protocol.
• ARINC 429, one of the most prevalent ARINC (Aeronautical Radio
INCorporated) standards, defines the transfer of digital data between com-
mercial avionics systems. It uses broadcast bus topology and a label
identification method for data words. ARINC 575 is the specification for a
Digital Air Data System (DADS). ARINC 575 includes a databus protocol
almost identical to ARINC 429.
• ARINC 708 defines an airborne pulse Doppler weather radar system for
commercial aircraft. The Transmitter/Receiver unit sends data over the 708
display databus to the Control/Display Unit. Data consists of 1600-bit words
that are preceded and followed by a sync. The display databus is an adapta-
tion of the proposed, but never approved, ARINC 453 databus.
• ARINC 717 includes the databus protocol for interconnecting the Digital
Flight Data Acquisition Unit (DFDAU) and the Digital Flight Data Recorder
(DFDR). Data words are 12 bits long and are nominally transmitted at 64 or
256 words per second in subframes, frames, and sometimes superframes.
ARINC 573, an older equipment specification for flight data recorders, uses
a databus similar to 717.
These and other standards are not limited to use in aircraft. They are used in
many other military and industrial applications such as surface and space vehi-
cles, process control, nuclear research, and oil exploration.
1.4 Other Documentation
Besides this manual, Ballard provides other documentation to facilitate operation
of the OmniBus interface. These include protocol manuals, information on the
software distribution disk, and CoPilot documentation.
Separate BTIDriver API programming manuals are available for each avionics
protocol. These manuals provide information on the specific protocol and include
basic and advanced programming instructions for users who intend to write their
own software. They also contain a comprehensive reference for each function.
1-4 OmniBus II PCIe/PXIe User’s Manual
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