DIGITAL COMMAND CONTROL - WHAT IS IT?


Information obtained from the Web

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In the year 2000, within Australia, this relatively new technology of Digital Command Control (or DCC as it is most commonly known) had a small group of people, within the Adelaide area, extremely interested in this new technology, so much so that, and as a result of this new technology, the DECCA Model Railway Club was founded, being the first DCC Club within the whole of Australia.  This new technology of Digital Command Control, amongst other things, allows the operator of any DCC System to operate and control a multitude of locomotives, trains and/or any other objects, for that matter, on or about the layout independently of each other and at the same time, on any selected section of the trackwork or anywhere else on the layout with varying speeds, different directions and control and even on the same electrically controlled section of track on the layout with complete ease of operation and without any interference to others utilising the layout.  Any type of complex wiring and/or the blocking of independent sections of the layout is now not required due to this new concept of the Digital Command Control technology.

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The Digital Command Control System consists, primarily, of a Command Module, Power Booster and a Hand Controller, to which many other ancillary items of the DCC System can be included at some time later, which will increase the operational efficiency of the DCC System.  The DCC System becomes operational when the Command Module is connected by two wires to a suitable mains power transformer.  Another two wires, from the Command Module, are connect directly to any two pair of tracks on the layout after which the tracks have been suitably prepared to accept the DCC System's track wires, giving these tracks a live, active connection to these tracks at all times whilst switched on; here a short circuit is imminent.  Fortunately, the DCC Systems are all protected against any type of short circuit; they will simply shut down before any damage is done.  The Hand Controller is also connected to the Command Module by way of a five (5) pin DIN plug.  Now that the DCC System is up and running, a decoder equipped locomotive is now ready to be positioned onto these live tracks.  The decoder equipped locomotive can be either a locomotive purchased with a decoder already installed or by inserting a decoder, which can easily be done by following the manufacturer's instructions implicitly, otherwise, come along to one of our meetings and any one of the members of the DECCA Club would be more than happy to assist you in any way possible of installing a decoder into a locomotive, you might even like to join the DECCA Club.  Once the decoder is installed into the locomotive, it is now time to 'set it up' by changing some of the Configuration Variables (or CVs), firstly by changing the address of the decoder by utilising the DCC System's Hand Controller (the manufacturer's default address is always #3); for which a programming track is needed to undertake this task and by following the manufacturer's instructions, the task is made quite simple enough.   Again, any one of the DECCA Club members would be more than willing to assist in this task of changing any one or more of these CVs.

 
This DCC System's technology will allow for any or all of the functions of the decoder chip, within each of the individual locomotives or objects on or about the layout, to be turned on or off, such as, the headlight's function, also the cabin lights and the flashing ditch light's functions, plus the smoke in a steam locomotive or even all or some of the street and/or building lights in and around the layout and much, much more, thanks to this new concept of DCC and utilising the DCC System's Hand Controller or any other similar device suitable for these tasks. 
All of the locomotives and/or objects in and around the layout, including any of the points and signals can now be fitted with either of the following decoder chip types: 1. a full sound decoder;  2. a mobile decoder;  3. a function only decoder:  4. an accessory decoder:  5. a stationary decoder.  The locomotives and the layout can now be operated just like the real thing.  These enhanced capabilities and the running abilities of a single locomotive utilising this DCC technology on this type of system now means that each and every one of the locomotives on the layout can now be operated at a steady, slow speeds and the locomotives can have controlled acceleration and braking, which is all dependent on the operator's Hand Controller or any other similar device.


The DCC System operates by using multiple digital data packets (or messages) that originates from the Hand Controller, which is connected to the Command module, and these packets are then transmitted from the Command module to the locomotive's decoder chip, which has its own unique address number.  These packets travel to the selected locomotive via these two tracks on the layout, communicating with this unique decoder chip that has been addressed by utilising its own unique identification number within that particular locomotive, coaches and/or any other rolling stock or object, for that matter, that has been fitted with some type of decoder chip on or about the layout.  Each locomotive, piece of rolling stock or other object that has a decoder chip fitted has it's own individual/unique address number that can be set by the user and accessed at any time via the DCC System's Hand Controller.

All of the DCC System's decoder chips are designed to suit any and/or all of the model railway scales from the smaller N-scale to the larger G-scale; it is interesting to note that now the smallest scale of Z - scale is now in the market for the use of decoder chips for this scale.  To view the photographs of some of these DCC Systems that are available to the public, select the link here ==>  Archives_&_Galleries  or from the selection of this menu option on the top, left of this page and then follow the link to the  System Photographs  page from there.  For more information on the DCC Systems that are available, follow the link to the manufacturers of some of these more popular DCC Systems that have been included, select the link here ==>  Links   or from the selection of this menu option on the top, left of this page.

 

 DE-MYSTIFYING DCC


 by Richard Johnson (of DCC Concepts)

 

Seldom has there been a concept that was designed to simplify and improve the performance of something as simple as a model railway system been so totally confused and complicated by the misinformed marketers, overenthusiastic supporters and the unnecessary new words.  Forget the nonsense; it is simple and it will transform the quality of running and operations on your layout.  Continue to read this page and we are sure you will understand the basics and be convinced!

So what is the big difference?

With DC control; there are several pickups that are attached to the locomotive that makes contact with the locomotive's wheels and transfers the power from the tracks, through the wheels and delivers it directly to the motor.  All of the layout is divided into selectable or isolatable track sections and the controller is connected to these individual sections of track as needed.  The concept of running multiple trains needs to have multiple controllers.  The locomotive will change speed and direction based on the individual controller varying the DC output voltage and the polarity of that section of individual track.  All of the locomotives on the same section of track will react in the same manner, with no fixed directional relationship between forward and reverse as this is purely dependent on the polarity being used in that section of track, which is controlled by the individual operator.  Tuning a locomotive's performance with a DC layout is almost impossible without changing the gearbox or the motor.  Therefore, any lights on the locomotives or the rolling stock will vary with the voltage, low speed means low voltage and stalling is, therefore, common unless the track is in perfect condition.

With DCC control; each of the locomotives on the layout has its own specific decoder chip installed within it and in some secluded spot (it is tiny and it can be as small as your little finger nail).  This decoder chip acts as a receiver for a digital data signal created by the controller into packets (messages), which travels around the track of the layout until it reaches the specific decoder chip within the specific locomotive with that individual/unique address number that has been specified by the controller.  Because every individual locomotive has been given its own unique/individual digital address via the hand controller (nothing more complicated than the number on the side of its cab) and the locomotive will only respond when it is specifically addressed by the controller by using that unique identification number.  The whole layout is treated as a single section of track with live rails at all times.  Each locomotive on the layout is able to be operated independently of others and there is no unwanted interaction with other locomotives, so there is no operational need for separate controllers or isolated sections of track on the layout as a whole.

Because of the fact that the
DCC system provides full voltage to the track at all times, locomotives and coach lighting is always constant and the availability of higher track voltage means that starting and slow speed running are often significantly better than when the same locomotive runs on a DC system.

The DCC system is, undoubtedly, one of the most exciting developments in the model railroading technology today, it gives all of the operators the ability to control every decoder chip equipped locomotive individually on the layout with the DCC system's hand controllers, rather than using toggle switches to control the layout track under a DC system.  This adds greatly to the practicability of model railway operations.  Manufacturers make decoders for all scales of model trains; mobile decoders for the locomotives and stationary decoders to control other things like points or lighting effects or other objects on the layout.   In addition to decoders, the manufacturers produce some of the most affordable and reliable Command Stations, Power Boosters, Hand Controllers, Transformers and even fully equipped sound decoders, transponding and detection equipment and DCC accessories are also available.  Some manufacturers provide complete DCC Starter Sets for the beginners at exceptional prices and with lots of value. 

 

Tuning a locomotive and changing acceleration, starting performance, momentum and top speed with DCC can be accomplished by simply changing a few of the instructions given to the motor via the decoder chip settings on a programming track.  This is simple to do with any of the DCC Controllers and it can be done separately for every one of the locomotive; in some cases, where warranted, several locomotives can be programmed together.  These settings are called Configuration Variables (or CV's) and are simply numbers entered by the keypad on the Hand Controller while the locomotive (or several locomotives) is/are in a special programming mode.  For more detailed information on the DCC systems, visit the DCC Concepts Website.  A link to that particular website can be found by selecting the link here ==> Links  or from the selection of this menu option on the top, left of this page.

 

The origins of the DCC systems can be traced back to the 1940s when Lionel Trains introduced a commercial two-channel system using frequency control.  An oscillator generated different frequencies, depending on which button an operator might press.  Then a tuned circuit and relay in each engine controlled the direction of the train.  General Electric, in the early sixties, introduced a five-channel commercial carrier control system called ASTRAC (Automatic Simultaneous Train Control), which could control more than one train per block.  Systems such as Dynatrol's CTC-16 from the late 1970s were more popular but suffered from lack of compatibility among competing systems.  This is partly why the National Model Railroad Association (NMRA) introduced standards for Digital Command Control based on the proposal by Lenz.  All manufacturers have to abide by this standard in order to receive NMRA conformance approval.  As a result of NMRA conformance standards, a digital signal from a Command Station can be received by any number of commercially available decoders.

 

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