Digital Command Control

Digital Command Control (DCC) is a standardized communication protocol for the control of model railways. Products conforming to DCC standards are therefore compatible regardless of manufacturer, enabling interoperability between all model railways running DCC. The standards and recommended practices that define DCC are developed by the DCC Working Group of the National Model Railroad Association (NMRA). The DCC logo trademark is owned by the NMRA. The most apparent feature of DCC is that it allows independent control of model locomotives occupying the same section of track by encoding a digital signal into the electrical waveform, for which to power locomotives, to communicate directly with the desired locomotive. This is in contrast to analog control schemes where locomotives are required to be in electrically isolated sections of track to be independently controlled. Since locomotives move along the track by nature, coordination is required to couple two sections of track before a locomotive bridges (electrically shorts) the gap between them and to prevent two locomotives from occupying the same section of track. On a DCC railway, all locomotives receive the same electrical signal, but each locomotive only responds to the commands that are addressed to itself. This feature gives rise to the expression that DCC requires "only two wires". DCC has enabled a high degree of portability, configurability, and extensibility to model railroading. Users are able to bring locomotives and throttles to model rail layouts at homes, clubs, and large meetups without worrying about compatibility. Users are able to customize locomotive behaviours and controller settings to their liking. Manufacturers are able to produce a wide variety of products with different purposes that are ensured to work with other standard-conforming products.