ARINC 429 is the 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

Local area network

A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...

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ARINC 429 is application-specific standard for aircraft avionics. It's a self-clocking, self-synchronizing data bus (Tx and Rx are on separate ports) known as the Mark 33 Digital Information Transfer System (DITS).