Digital model railway control systems
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A variety of model train control systems are available to operate locomotives on a model railways. The earlier traditional analog systems where the speed and the direction of a train is controlled by adjusting the voltage on the track are still popular while they have recently given way to control systems beased on computer technology. Digital model railway control systems are the modern alternative to control a layout and greatly simplify the wiring and add more flexibility in operations.
Digital model railway control system basics
Modern digital control systems provide the ability to independently control all aspects of operating a model railway using a minimum of wiring; often the rails themselves are the only runs of wiring required. Control is achieved by sending a digital signal down the rails. These digital signals control operation of some, or even all aspects, of the model trains and accessories, including signals, turnouts, level crossings, cranes, turntables, and so forth.
Depending of the system, it may contain the following components:
Throttle
A throttle is a unit which controls operation of a train. Throttles are also known as Cabs, particularly in the US. A throttle can control speed and direction of one train at any time. The throttle also offers some means to select one of many trains which may be operating on a layout.
Central Unit
The central station is the heart of the digital system. The Central Unit receives commands from Throttles (and possibly other sources), and emits the appropriate digital signals onto the track, to implement the commands issued by the throttle or by other sources. Most Central Units include an integrated Booster.
Booster
A Booster amplifies a low-power digital signal produced by the Central Unit, to the power levels needed to operate trains. Boosters are typically limited to a power output of 3 to 4 Amps. With HO or smaller track, currents higher than 4 Amps are high enough that short-circuits caused by a derailment can spot-weld the derailed wheels to the track.
In large layouts, where the total current requirement is higher, the track will be partitioned into multiple segments, and each segment will be powered by its own digital booster. The boosters may receive digital signals via a direct cable from the Central Unit, or simply from the track of an adjacent Booster segment.
Locomotive Decoder
Locomotive decoders are small electronic devices which are fitted inside locomotives. The decoder interprets the digital signal sent from the Digital model railway control systems#Central Unit]] to the rails. When the Central Unit sends commands to change the speed, direction, or other aspects of this locomotive, the decoder alters the electrical feed to the motor accordingly.
Stationary Decoder
Stationary decoders are used to control operating devices which are fixed in position, such as turnouts, (eng.Points) signals, level crossings, and other devices. Since the devices do not move, stationary decoders can be mounted under the layout, and therefore can be significantly larger than locomotive decoders.
Sound and Function Decoders
Basic locomotive decoders provide control of speed and direction, and little else. Supplemental decoders can be placed into a locomotive, to control headlights, ditch lights, or movable non-traction components such as remote-controlled pantographs. These decoders are called Function Decoders.
Sound decoders are, in essence, a miniature PC sound-card with pre-recorded sounds. The sound effects are played in synchronization with the locomotive, 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 in synchrony with rotation of the driving wheels.
Some decoders have all three functions—locomotive control, sound effects, and function control—in a single device.
Feedback Bus
To automate a digitally-controlled model railroad, the Central Unit needs to know when trains reach their destination, or when the train reaches a certain point. This information is detected by a sensor, such as an infrared device placed between the tracks, or a device which senses current-draw in a particular section of otherwise-isolated track.
The Feedback Bus is the device which relays an electrical signal—an "on" condition—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 specific signal, or level crossing.
The advantage of feedback is that each device typically needs only two wires: one to each digital track signal.
Computer Interface
Some Central Units
Systems
Digital Command Control
Digital Command Control (DCC) systems are used to operate locomotives on a model railroad (railway). Equipped with DCC, locomotives on the same electrical section of track can be independently controlled. 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.
Digital Command System
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Digital Command System (DCS) is an electronic control system for O scale 3-rail and now HO scale model trains and toy trains, developed by MTH Electric Trains as a rival to Lionel's Trainmaster Command Control. It is similar in concept to DCC, the open industry standard used by HO scale and other 2-rail direct current trains.
It permits operation of multiple MTH ProtoSound 2.0 (PS2.0) engines on the same track without complex wiring, and also gives locomotives realistic digitized sounds.
Unlike Lionel, MTH has not licensed its standard to any other company. While MTH's DCS will not operate TMCC locomotives directly and Lionel's TMCC will not unlock all the control features of PS2.0 engines, the two systems will easily operate side by side on the same track. Therefore engines with either system can be operated simultaneously as long as both command control units are installed on the track.
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.
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 electronic control system for O scale 3-rail model trains and toy trains. Conceptually it is similar to Digital Command Control (DCC), the industry's open standard used by HO scale and other 2-rail DC trains. It has one advantage over DCC, in that TMCC-equipped locomotives can run simultaneously with non-TMCC locomotives.[1]
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.
Rocrail
Rocrail is an Open Source Project that can control a model train layout from one or more computers. You can run trains directly from your computer, and you can have the computer run trains automatically for you. You can even have some of the trains on your layout running automatically while you control others by hand.
References
External links
- DCCWiki - Community DCC site for model railroad.