The Commercial Standard Digital Bus (CSDB) is a

multidrop bus A multidrop bus (MDB) is a computer bus able to connect three or more devices. A process of arbitration determines which device sends information at any point. The other devices listen for the data they are intended to receive. Multidrop buses hav ...

, formerly known as the Collins Standard Digital Bus. The maximum speed is 50 kbit/s. Most civilian aircraft use one of 3 serial buses: the Commercial Standard Digital Bus (CSDB), Cary Spitzer. "The Avionics Handbook". Lee Harrison
Chapter 3: Commercial Standard Digital Bus

ARINC 429 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 interface ...

, or AS-15531. The Commercial Standard Digital Bus is a two-wire

asynchronous Asynchrony is any dynamic far from synchronization. If and as parts of an asynchronous system become more synchronized, those parts or even the whole system can be said to be in sync. Asynchrony or asynchronous may refer to: Electronics and com ...

broadcast

data transmission Data communication, including data transmission and data reception, is the transfer of data, signal transmission, transmitted and received over a Point-to-point (telecommunications), point-to-point or point-to-multipoint communication chann ...

bus. Data is transmitted over an interconnecting cable by devices that comply with

Electronic Industries Association The Electronic Industries Alliance (EIA; until 1997 Electronic Industries Association) was an American standards and trade organization composed as an alliance of trade associations for electronics manufacturers in the United States. They dev ...

(EIA) RS-422A. The physical layer is

EIA-422 RS-422, also known as TIA/EIA-422, is a technical standard originated by the Electronic Industries Alliance, first issued in 1975, that specifies the electrical characteristics of a digital signaling circuit. It was meant to be the foundation ...

. Messages on the CSDB consist of one address byte followed by any number of data bytes."Commercial Standard Communications Bus"

References

Avionics Serial buses {{Aviation-stub