Commercial Standard Digital Bus
{{More citations needed|date=September 2017}}
The Commercial Standard Digital Bus (CSDB) is a multidrop bus, formerly known as the Collins Standard Digital Bus. The maximum speed is 50 kbit/s.{{Citation needed|date=December 2018}}
Most civilian aircraft use one of 3 serial buses: the Commercial Standard Digital Bus (CSDB),
Cary Spitzer.
"The Avionics Handbook".
Lee Harrison.
[http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_3.pdf Chapter 3: Commercial Standard Digital Bus]
The Commercial Standard Digital Bus is a two-wire asynchronous broadcast data transmission bus. Data is transmitted over an interconnecting cable by devices that comply with Electronic Industries Association (EIA) RS-422A. The physical layer is EIA-422.
Messages on the CSDB consist of one address byte followed by any number of data bytes.
[http://www.interfacebus.com/Avionics_CSDB_Interface_Description.html "Commercial Standard Communications Bus"].