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The data transfer standard for aircraft avionics is called ARINC 429.

ARINC is the dominant factor in avionics data bus technology. As a dual wire differential, it can allow connectivity to one transmitter and can be a source for up to 20 receivers.

ARINC 429 employs a self-synchronizing, self-clocking data bus protocol. Data words are 32 bits in length with messages generally have a single data word.

Bits 11 through 29 are responsible for containing the data itself in several formats. These formats include Bit Field, Binary Coded Decimal (BCD), and Binary Number Representation (BNR). Bits 9 and 10 function as Source/Destination Identifiers (SDI) for the transmitting system. SDI identifies the source that is transmitting the data. It can also identify the receivers that the data is intended for. Bits 1-8 are octal label words that identify the type of data being transmitted.

As an alternative to MIL-STD-1553, ARINC 429 employs several physical, electrical, and protocol techniques to minimize electromagnetic interference with on-board radios and other equipment. Its cabling is a shielded 70 Ω twisted-pair.

ARINC signaling defines a 20 Vp differential between the Data A and Data B levels within the bipolar transmission (i.e., 10 V on Data A and -10 V on Data B would constitute a valid driving signal), and the specification defines acceptable voltage rise and fall times.

ARINC 429’s data encoding uses a complementary differential bipolar return-to-zero (BPRZ) transmission waveform, further reducing EMI emissions from the cable itself.

The thing that makes ARINC 429 so crucial to flight is the fact that label guidelines for flight equipment are part of its specification. Each aircraft contains a number of different systems. This list of systems could include flight management computers, radios, GPS sensors and inertial reference systems.

There is a high degree of uniformity among all manufactures and models to allow for cooperation and interchangeability between parts. ARINC 429 plays a role in ensuring that protocols stay consistent among all these parts that come from various sources.

Want to know more about ARINC 429? Tonex offers ARINC 429 Training, a 2-day course that covers the ARINC 429 specification and how it defines a local area network for transfer of digital data between avionics system elements and subsystems. 

Additionally, Tonex offers another 45 courses in Aerospace & Defense Engineering, including:

Additionally, Tonex offers another 45 courses in Aerospace & Defense Engineering, including:

Combat Systems Engineering Training (3 days)

Advanced Link 16 Training (3 days) 

DO-178 Training/DO-178C Training/DO-254 Training (4 days)

Applied Systems Engineering for Logisticians (3 days)

Intro to Fiber Optics and Infrared Sensors (3 days)

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