ARINC 429: Ұшақ авионикасының деректерді тарату протоколы

Communications protocol
ARINC 429, the "Mark 33 Digital Information Transfer System (DITS)," is the ARINC technical standard for the predominant avionics data bus used on most higher end commercial and transport aircraft. It defines the physical and electrical interfaces of a two wire data bus and a data protocol to support an aircraft's avionics local area network.

ARINC 429 is a data transfer standard for aircraft avionics. It uses a self clocking, self synchronizing data bus protocol (Tx and Rx are on separate ports). The physical connection wires are twisted pairs carrying balanced differential signaling. Data words are 32 bits in length and most messages consist of a single data word. Messages are transmitted at either 12.5 or 100 kbit/s to other system elements that are monitoring the bus messages. The transmitter constantly transmits either 32 bit data words or the NULL state (0 Volts). A single wire pair is limited to one transmitter and no more than 20 receivers. The protocol allows for self clocking at the receiver end, thus eliminating the need to transmit clocking data. ARINC 429 is an alternative to MIL STD 1553.

Label guidelines are provided as part of the ARINC 429 specification, for various equipment types. Each aircraft will contain a number of different systems, such as flight management computers, inertial reference systems, air data computers, radar altimeters, radios, and GPS sensors. For each type of equipment, a set of standard parameters is defined, which is common across all manufacturers and models. For example, any air data computer will provide the barometric altitude of the aircraft as label 203. This allows some degree of interchangeability of parts, as all air data computers behave, for the most part, in the same way. There are only a limited number of labels, though, and so label 203 may have some completely different meaning if sent by a GPS sensor, for example. Very commonly needed aircraft parameters, however, use the same label regardless of source. Also, as with any specification, each manufacturer has slight differences from the formal specification, such as by providing extra data above and beyond the specification, leaving out some data recommended by the specification, or other various changes.

Avionics systems must meet environmental requirements, usually stated as RTCA DO 160 environmental categories. ARINC 429 employs several physical, electrical, and protocol techniques to minimize electromagnetic interference with on board radios and other equipment, for example via other transmission cables. Its cabling is a shielded 70 Ω twisted pair. ARINC 708 defines a protocol for transmission of weather radar data. While the 708 transmission is a simplified version of MIL STD 1553, control of ARINC 708 components was standardized through ARINC 429 labels. ARINC 828 defines Electronic Flight Bag (EFB) interfaces used in all types of aircraft and includes, among other interfaces, ARINC 429 interfacing. MIL STD 1553, Military Bus standard for a "Shared Serial Bus", often used in place of ARINC 429.