Aeronautical Radio INC (ARINC) is an organization composed of major airlines and airplane manufacturers, which promotes standardization within aircraft equipment. To facilitate this end ARINC puts out specifications describing communications busses as well as certain types of avionics systems. One of the more popular busses used in commercial aircraft today is the ARINC-429 bus.
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. ARINC-429 connects a single transmitter or source to one or more receivers or sinks. Two speeds are defined, 12.5 kHz and 100kHz. The ARINC specification defines not only the physical layer and electrical characteristics but the data format of data sent over the bus as well.