UIC 568
The UIC 568 standard from the International Union of Railways, describes a 13-conductor cable and connectors used for transmitting a variety of data and commands between a locomotive and passenger carriages. Examples of those commands and data is loudspeaker messages, train destination signs, and control of doors and others. Since 1996 this standard number has been reused for "Loudspeaker and telephone systems in RIC coaches Standard technical characteristics". The current standard is given in UIC leaflet 558 "Remote control and data cable – Standard technical features for the equipping of RIC coaches".
History
The UIC 568-cable and connector was first introduced along with the specifications for carriages built according to the UIC type Y and the UIC type X, but have later on been used for variety of other passenger carriages, allowing mixing of InterCity and regional carriages.Remote operation of locomotive
Very early in the development of the standard, it was decided that two conductors and pins should be reserved for remote operation of the locomotive.Locomotives equipped according to this standard will usually have two sockets at each end of the locomotive, and carriages will usually also have one or two sockets. Loose cables are then used to establish connection between the locomotive and the carriages, as well as from carriage to carriage.