The ARINC 429 Specification defines basic requirements for the transmission of digital data between commercial avionics systems.

For ease of design implementation and data communications, signal levels, timing, and protocol characteristics are specified.

ARINC 429 is designed to provide the interchangeability and interface of commercial aircraft Line Replaceable Units (LRUs).

As in a layman’s term, ARINC protocol is designed to support communication in the Local Area Network (LAN) of the avionics

ARINC 429 is also known as the Mark 33 Digital Information Transfer System (DITS) bus. Although used mostly in the field of avionics, these buses are also used in the field of ground vehicles, weapons systems, and other commercial and military equipment.

The word structure, the electrical component characteristics, and the protocol needed for the requirement of successful communication is defined in the specifications. The Simplex, twisted shielded pair data bus standard Mark 33 DITS bus is used by ARINC 429. Both the hardware and data formats needed for bus transmission are specified by ARINC 429.

A single connected transmitter or source consists of the hardware connected to from 1-20 receivers or sinks on one twisted wire pair. Data can only be transmitted in one direction (unidirectional connection), for bi-directional communication, it requires two channels or buses. FPGA

In a star or bus-drop topology, the modules, line replaceable units or LRUs, are most commonly configured. Multiple transmitters and receivers communicating on separate buses can be present in each LRU. Figure 1 shows the preferred connection topologies for the data bus. This simple architecture provides a highly efficient transfer of data, almost node-to-node connectivity.

A transmitter can only talk to a number of bus receivers, up to 20 on a single wire pair, with each receiver monitoring the related data continuously, but not accepting data reception. When large quantities of data have been transmitted, a transmitter can require acknowledgment from a receiv

As compared to a hard-wired handshake, this handshaking is done using a specific word style. Two twisted pairs comprising two channels are sufficient to carry information back and forth, one for each direction when this two-way communication format is needed.

The transmission of the LRU source consists of 32-bit words containing a portion of 24-bit data containing the actual data and an 8-bit label describing the data itself. LRUs do not have an address assigned by ARINC 429, but rather an equipment ID numbers that allow device management and file transfer of equipment to be grouped into systems WeTransfer Alternative