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Encyclopedia > Digital Command Control
A Digitrax DCC system
A Digitrax DCC system

Digital Command Control (DCC) is a scheme for controlling locomotives on a model railroad layout that allows one or more locomotives to be independently controlled on the same electrical section of track. The Digitrax Super Chief DCC system installed on the Trewsville Southern Railroad. ... The Digitrax Super Chief DCC system installed on the Trewsville Southern Railroad. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A locomotive (from Latin loco motivus) is a railway vehicle that provides the motive power for a train, and has no payload capacity of its own; its sole purpose is to move the train along the tracks. ... This article needs cleanup. ...

Contents

How DCC works

Each of the locomotives is equipped with a mobile DCC decoder that receives signals from the track and provides power to the motor and any lights the model may have. While DCC is only one of several alternative systems for digital model train control, it is often misinterpreted to be a generic term for such systems. A Digitrax DH163AT DCC decoder in an Athearn locomotive before the shell goes on. ... Rotating magnetic field as a sum of magnetic vectors from 3 phase coils An electric motor converts electrical energy into kinetic energy. ...


In DCC, a Command station and booster combination places both the power and the messages on the track using a scheme where the actual power modulation encodes the digital bits of the messages. A stationary decoder can also be attached to the rails at a fixed spot, to allow control of switches and lights. For delivered electrical power, see Electrical power industry. ... In telecommunications, modulation is the process of varying a periodic waveform, i. ... This article is about the unit of information. ...


The key advantage of using DCC over traditional DC systems is the simplification of the wiring required to operate more than one locomotive on any layout at the same time. DCC makes it easier to run more than one train at a time. Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...

A short, mid packet, example of a DCC signal and its encoded bit stream.
A short, mid packet, example of a DCC signal and its encoded bit stream.

DCC uses bipolar DC, which is a form of alternating current, to provide power and transmit data, while traditional systems use DC for power. Because the power is bipolar DC, the DCC signal does not follow a sine wave. Instead, the control system quickly switches the direction of the DC current, resulting in a square wave. The length of time that the current is flowing in each direction provides a method for encoding data. To represent one, the time is short (nominally 58µs for a half cycle). A zero is represented by a longer period (nominally 100µs for a half cycle). Image File history File links DCCsig. ... Image File history File links DCCsig. ... City lights viewed in a motion blurred exposure. ... In trigonometry, an ideal sine wave is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C, where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C... A square wave is a kind of basic waveform. ...

A DCC decoder installed in a N scale steam locomotive.
A DCC decoder installed in a N scale steam locomotive.

Image File history File linksMetadata Download high resolution version (1600x1200, 187 KB) Summary A DCC decoder installed in an N scale LifeLike Berkshire Licensing I, the creator of this work, hereby release it into the public domain. ... Image File history File linksMetadata Download high resolution version (1600x1200, 187 KB) Summary A DCC decoder installed in an N scale LifeLike Berkshire Licensing I, the creator of this work, hereby release it into the public domain. ... U.S. Prototype model of an N scale (1:160) Chesapeake and Ohio Railway 2-6-6-2 shown with a pencil for size N scale (or sometimes N gauge) is a popular model railway size, allowing hobbyists to build layouts that take up less space than HO scale, or...

DCC can normally power a single analog model locomotive

In a segment of DCC-powered track, it is possible to power a single analog model locomotive by itself or in addition to DCC-aware engines through a method known as zero stretching. In this scheme, zero bits on the track can be extended to create a net effect where current appears to the engine to be flowing in one direction or another. However, because the power is actually closer to AC, many DC motors heat up much more quickly than they ordinarily would on DC power, and some motor types (particularly coreless electric motors) can be damaged by a DCC signal. Rotating magnetic field as a sum of magnetic vectors from 3 phase coils An electric motor converts electrical energy into kinetic energy. ...


DCC protocols

The DCC protocol is the subject of two standards published by the NMRA: S-9.1 specifies the electrical standard, and S-9.2 specifies the communications standard. Several recommended practices documents are also made available. The Standards and Recommended Practices are available here. Standardization, in the context related to technologies and industries, is the process of establishing a technical standard among competing entities in a market, where this will bring benefits without hurting competition. ... The National Model Railroad Association or NMRA is a non-profit organization for those involved in the hobby or business of model railroading. ... It has been suggested that this article or section be merged with protocol (computing). ...


DCC compared with other systems

There are several competing digital train control systems, most notably the European standard, Selectrix, and the proprietary Märklin-Motorola system, which is used exclusively in the model train products of Märklin company. DCC, however, is the most widespread system. One of the reasons for this is that it is a widely adopted standard both in North America and in Europe. DCC was originally developed by German company Lenz that decided to allow their system to become an open standard. As a result, DCC was adopted as a standard by the National Model Railroad Association and it is also a NEM standard. Selectrix is a digital model train command control system developed by German company Döhler & Haas for model railway manufacturer Trix in early 1980s. ... An O scale Mitropa sleeping car made by Märklin Märklin (or Maerklin) is a German toy company, founded in 1859. ... The National Model Railroad Association or NMRA is a non-profit organization for those involved in the hobby or business of model railroading. ... Normen Europäischer Modelleisenbahnen (NEM) are standards for rail transport modelling valid for constructing models of European railways, issued by the MOROP (European union of model railway and railway friends). ...


DCC manufacturers

It has been suggested that Bachmann Branchline be merged into this article or section. ... Electronic Solutions Ulm (known as ESU) is a German manufacturer of accessories for model trains, especially known for their locomotive decoders. ... Hornby Railways is the leading brand of model railway in the United Kingdom, and its company roots date back to 1901, when founder Frank Hornby received a patent for his Meccano construction toy. ...

See also

Digital Command System (DCS) is an electronic control system for O scale 3-rail model trains and toy trains, developed by MTH Electric Trains as a rival to Lionels Trainmaster Command Control. ...

External links


  Results from FactBites:
 
DCC FAQ 1.9 (3996 words)
Several existing command control manufacturers are working to produce products that conform to the standard as well as to continue to support their existing system and product base.
A: Although simple low end digital command stations that only provide for control of a limited number of engines simply cycle through all the addresses in use repeatedly, higher end systems may use a priority based scheme so that packets that contain values that have changed are sent before packets that are repeats.
If a digital decoder supports analog operation, and does not see a digital signal on the track, it reverts to analog operation and can be controlled as if no digital decoder were present.
DCC Tips (20978 words)
One common feature of command control is that each engine carries some form of command receiver that controls the motor (or throttle in the case of live steam) of a locomotive in response to commands directed to that particular locomotive.
DCC systems shouldn't require that crystals be changed, transmitters be reprogrammed or receivers be relinked to share a single radio throttle between all the engines on the layout.
DCC has the ability to use a programmable speed table so that engines that naturally run at different speeds can be equalized so that they run at the same speed over their entire speed ranges.
  More results at FactBites »

 
 

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