Digital model railway control systems are computer-based control system for the programming and operation of locomotives on model railways. While traditional analogue systems control the speed and the direction of a train by adjusting the voltage on the track, digital command systems allows users to program locomotives through a controller. There are a number of digital model railway control systems available for purchase and because they are based on computer technology rather than hardware, these systems provide modellers with a simplified and flexible alternative to analogue systems that may be more accessible for the average user.
Digital model railway control systems provide the ability to independently control all operating aspects of a model railway using minimal wiring. In some cases the rails themselves can be the only wiring required, while other systems are completely wireless. In the absence of wiring, control is achieved by sending a digital signal as well as power down the rails or wirelessly through Wi-Fi or Bluetooth. These digital signals can control all aspects of the model trains and accessories, including signals, turnouts, lighting, level crossings, cranes, turntables, etc.
Constant power is supplied to the track and digital signals are sent which require electronic decoders to be fitted to locomotives and other devices to interpret the commands.
Components Controllers Controllers manage operation of locomotives with buttons for all features of a locomotive, from speed and direction to lighting and sound. The style and features of a controller differ between providers and range in size and design. Some controllers feature screens that display information, while others have dials or joysticks.
Central Unit A digital system usually requires a central unit to generate digital address and command signals, these are known as command stations. Many command stations also incorporate one or more locomotive controllers and a booster unit to generate the power necessary to run locomotives. Central units also have connections for additional controllers and accessory switch boxes, as well as connections for computer control and interfaces with other digital controllers.
Boosters In most systems, boosters are available to provide additional track power for larger layouts. Boosters are connected to the central unit by special cables that relay the digital commands.
Decoders Basic locomotive decoders provide control of speed and direction while supplemental function decoders control headlights, ditch lights, or movable non-traction components such as remote-controlled pantographs. Some decoders have control over the locomotive, sound effects, and other layout functions in a single circuit.
Locomotive decoders are small electronic circuits fitted inside locomotives to interpret the digital signals and provide individual control. Although all active decoders receive commands, only the addressed decoder will respond.
Accessory decoders are used to control devices which are fixed in position, such as turnouts, signals, and level crossings. Since the devices do not move, stationary decoders can be mounted under the layout, and therefore can be significantly larger than locomotive decoders. Accessory decoders can receive their signals from an accessory data bus or from the track.
Sound decoders play pre-recorded sound effects which may be synchronised with the locomotive speed, so that as a diesel locomotive starts from standstill, the sound decoder plays sounds of a diesel engine starting up. Sound decoders for steam locomotives can play "chuff" sounds synchronised with the driving wheels.
Feedback In some automated systems, the central unit needs to know when trains reach their destination or a certain point on the track. This information is detected by a sensor, such as an infrared device placed between the tracks, a reed switch or a device which senses current draw in an isolated section of track.
Feedback relays an electrical signal from the sensor hardware back to the digital central unit. The central unit can then issue commands appropriate for the specific sensor, such as triggering a signal, or level crossing.
Feedback allows fully automated control of model trains.
Computer interface Some central units allow connection to a computer, and a program can then fully automatically control all model train movements and accessories. This facility is particularly useful for display layouts.
Programs have been developed allowing mobile devices to be used as controllers, which also requires the central unit to be connected to a computer.
Systems Digital Command Control
Digital Command Control (DCC) systems is a standardized system used to operate locomotives on a model railroad (railway). Equipped with DCC, locomotives on the same electrical section of track can be independently controlled. This works by encoding a digital signal into electrical waves to communicate directly to a specific locomotive therefore controlling the unit without interfering with others on the line. The benefit of DCC is independent control of locomotives, interactive lighting and sound effects, simplicity of wiring, and standardized programming.
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. Several major manufacturers offer DCC systems, including Digitax
Digital Command System Digital Command System (DCS) is an electronic system developed by MTH Electric Trains and released in April 2002. DCS controls locomotives equipped with Protosound 2, Protosound 3, or Protosound 3E+ decoders. Protosound 3 locomotives are compatible with both DCS and DCC command systems. Protosound 3E+ locomotives are compatible with DCS and Märklin Digital command systems. All DCS compatible decoders are manufactured by MTH. Factory installed decoders have been offered in H0 scale, two-rail 0 scale, 3-rail 0 gauge, Gauge 1, and three-rail Standard Gauge models. MTH has announced their intention to install DCS compatible decoders in S scale trains beginning in 2013.mthtrains.com Separate sale decoder kits have been offered for installation in all of the above noted scales except H0 and S. DCS is predominantly used in three-rail O gauge. Its chief competitors in three-rail O are Lionel's TMCC and Legacy systems.
DCS uses proprietary command codes and transmission technology covered under US patent 6,457,681.protosound2.com The principal differences between DCS and DCC transmission technologies include bidirectional communications and the separation of the command signal from track power. DCS command signals are transmitted at 10.7 MHz using spread spectrum technology.
DCS can operate TMCC equipped models by means of an interface cable that connects the Lionel CB-1 command base to the DCS Track Interface Unit. DCS can coexist on the same track at the same time with either Lionel TMCC or Legacy command systems. Engines with either system can be operated simultaneously as long as both command control units are installed on the track.
Direct WiFi Control Direct WiFi Control (DWiC) is an emerging technology for model railway control utilizing the concept of "the internet of things". The availability of miniature web server modules in 2014, led to the formation of a DWiC Working group to explore the possibility of using this technology in model railways. WiFi technology is well established and proven. Although it is considerably more complex than any previous model railway control system it largely transparent to the user with tasks such as bi-directional communication being seamless. DWiC does not use any model rail specific items such as command stations and boosters and so is much lower in cost. This technology is also useful outside the model rail world as a DWiC controller could open a garage door or remotely turn on sprinklers. The web server/controller is similar to a DCC decoder in hardware and cost. The great advantage occurs on the client side where the "throttle" can be any WiFi device with a web browser. DWiC can run on DC, AC or DCC track power or a battery.
The DWiC controller has a web page loaded on board tailored to the particular "item" - loco, accessory etc. The users browser loads the page off the items web server and by pressing buttons directly controls the item via WiFi using HTML, JavaScript, JQuery and C.
Software Digital model railway control systems are often connected with an external computer where special software for controlling the train layout is running. This allows more options for operating trains from fully automatic system where the computer is in control of everything in a layout to a computer based control console for controlling signals and points on the layout and leaving the role of the train engineer to a human.
Providers Märklin Digital
Märklin Digital was one of the first digital model railway control systems. It consisted of a full system including locomotive decoders (based on a Motorola chip), central control, a computer interface, turnout decoders, digital relays and s88 feedback modules. For controlling 2-rail DC locomotives, like Märklin's Z and 1 gauge rolling stock, a special version of the system was introduced in 1988 developed by Lenz jointly for Märklin and Arnold. Arnold sold the system under name Arnold Digital while Märklin called it "Märklin Digital", this system was the predecessor of DCC-standard. Apart from the locomotive decoders and central units, all the other system components were identical between 3-rail and 2-rail versions.
Selectrix
Selectrix is an early digital model train command control system developed by German company Döhler & Haas for model railway manufacturer Trix in the early 1980s. Since 1999 Selectrix is an open system supported by several manufacturers and standardized by MOROP. Technically Selectrix differs from competing bus systems by being fully synchronized and bi-directional. The same data bus protocol and data buses are shared by the rolling stock, accessories and feedback information.
Trainmaster Command Control
Trainmaster Command Control (TMCC) is Lionel's original command control system. It was introduced exclusively in Lionel trains in 1995. Beginning in 2000, Lionel offered licenses to other manufacturers. Licensees that formerly or currently install TMCC decoders in their models include Atlas O, K-Line, Weaver, and Sunset Models 3rd Rail Division. Licensees that formerly or currently offer separate sale decoders include Train America Studios, Digital Dynamics, and Electric RR Co. TMCC decoders have mostly been installed in 3-rail O gauge models, but it has also been offered in 2-rail O scale and S scale.
TMCC utilizes the same command codes as Digital Command Control (DCC). However, unlike DCC, it uses a 455 kHz radio transmission to carry the command codes separate from track power. The locomotive decoders are dependent on AC track power (50 or 60 Hz) to synchronize the command receiver. Thus, TMCC can only operate on AC track power. Because TMCC utilizes the DCC command codes, it is possible to control TMCC with DCC compatible software. MTH Electric Trains included support to interface and control TMCC with its DCS system. Unlike DCC, TMCC-equipped locomotives can run simultaneously with non-TMCC locomotives. Lionel ceased the sale of TMCC command systems in 2010, but continues to introduce models equipped with TMCC decoders. TMCC has been superseded by Lionel's Legacy command system.digitdynam.com
Legacy Control System