Digital model railway control systems

A number of control systems are available to operate locomotives on 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 based 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 unit 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. The throttle can also be integrated in the central unit. Central units requiring a separate throttle device are often called black box style central units. Many central units are equipped with data bus connectors for controlling accessories or receiving feedback. There are several standardized data bus types used commonly in central units.

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, 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. Usually stationary decoders are connected to central unit's data bus connector, but it is also possible for stationary decoders to receive their data signal from the track.

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

Main article: 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

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

Main article: 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 variety of the system was introduced in 1988. The system was identical to Arnold Digital. Apart from the locomotive decoders and central units, all the other system components were identical between 3-rail and 2-rail versions.

Selectrix

Main article: 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

Main article: 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.

Hornby Zero 1

Hornby Zero 1 is a forerunner to the commercial Digital model railway control system developed by Hornby in the late 1970s. Zero 1 system offered simultaneous control of up to 16 locomotives and 99 accessories.The Hammond & Morgan digital train control system is totally compatible with the Zero One. Zero 1 was release in late 1979.

A multiple train control system named Zero 1 was introduced in late 1979. This control system was a forerunner to the Digital Command Control (DCC) system, an NMRA open standard, which appeared in the 1990s. Though an important milestone, Zero 1 was not widely successful; both the controller units and the decoder modules required for the locomotives were expensive, but with a clean track and well serviced locos the system worked well, control of points and other accessories was available in a very simple manor, locomotives equipped with a Zero 1 decoder could not be used on conventional systems, making it difficult to run one's locomotives on friends' layouts or club layouts.

Zero 1 had 3 'phased' introductions. Phase 1 = Master controller and basic system (Master controller, Slave, hand held slave unit and Loco modules) Phase 2 = Accessory control (Points, Signals etc) Phase 3 = Micro Mimic display (Allowed for LED'S to represent status of points and signals on a Mimic display panel)

The Main Master controller unit disscontinued in 1986, and finally the last time Loco Modules were listed was in the 1991 catalogue 'Limited supplies of R955 Loco module are available'. Repairs to Zero 1 units were no longer undertaken by Hornby due to them stating 'Lack of available parts required'.

The system is very reliable equipment, the basic 1980'S keyboard design being the main problem on older badly stored Master units. Easily repaired though and can be made to work like new in a few simple steps. Loco Modules were available in two types, pre 1981 were a single SCR/TRIAC based unit, the later made by H&M using two units, one for Forward, one for reverse. Again the Loco modules are easy to repair in the right hands.

The system is still used today by many modellers, highlighted by the demand on such sites like Ebay for the items in the second hand market. The unused sockets on the rear of the Phase 3 Mimic controller showed promise in the way development could have been heading. A Light Pen socket possible indicating a link to a computer and control via VDU Light Pen. Bear in mind this was the era of the Sinclair Spectrum which was launched 2 years after Zero 1, the system was perhaps ahead of its time. The DCC system which is today's current standard for Digital Control of a Model railway is similar in many ways to how Zero 1 worked.

Airfix Multiple Control System

Airfix Multiple Control System(MTC) was introduced in 1980 and used 20v AC on the track with a superimposed control signal. Unfortunately it was only produced for about 18 months when Airfix went into receivership and the concept was not developed but dropped. MTC system offered simultaneous control any 4 out of up to 16 locomotives.

DYNATROL

DYNATROL is a 15-channel command control system from Power Systems Inc.The track voltage is 13.5 volts d.c.It was introduced late 1970s.

Digitrack 1600

Digitrack 1600 is one of the first generation digital Digital model railway control system developed and marketed by Chuck Balmer and Dick Robbins in 1972. CTC-16 is a second-generation design based on the Digitrack 1600, a commercial system marketed from 1972 to 1976. The CTC-16 digital train control system is totally compatible with the Digitrack 1600.

Rail-Command 816

RAIL-COMMAND 816 is an 8-channel digital signal system using a 12 volts d.c.constant track voltage.It was introduced late 1970s.

CTC-16

CTC-16 system offered simultaneous control of up to 16 locomotives. A series of 16 pulses is sent out to the track 125 times each second. A receiver monted in each locomotive is tuned to respond to only one of the 16 pluses. The amount of voltage appliied to the motor depends on the width of the pulse commanding that paricular locomotive. The receiver decodes the programmed channel from the command signal and extracts the speed and direction information from it.The receiver is essentially a transistor throttle built right into the locomotive. The command station is not expandable beyond 16 channels.

PROTRAC

PROTRACR/C system 9000 offers 8-channel command control.It was introduced late 1970s.

SALOTA 5300

SALOTA 5300 offers 5-channel command control with a 16-to 18-volt d.c. constant track voltage. It was introduced late 1970s.

PMP-112

PMP-112 system offered simultaneous control of up to 112 locomotives. It was based CTC-16.

RFPT

RFPT offers 9-channel command control system using high-frequency control signals and a 12-volt a.c. constant track voltage.

KATO Digital

KATO Digital is KATO's electronic control system for HO scale model trains. Conceptually it is similar to Digital Command Control (DCC).It was introduced late 1980s.

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.

Hornby RailMaster

Main article: RailMaster

RailMaster is a new model railway control software package announced by Hornby, one of the world's largest model railway companies, at Christmas 2010. The software connects to the Hornby Elite DCC controller (at present) and allows for the controls of trains, points, signals, turntables and uncouplers from a single screen. Although you can use it with a normal mouse, it has been optimised for touch-screen PCs where you just touch a point, a signal or slide a locomotive throttle.

This link http://www.youtube.com/watch?v=hGfiuO2o9NQ is a video on YouTube showing the new system.

The new RailMaster software will be available to purchase during the second quarter 2011. Hornby aim to set the standard in PC model railway control software and have a comprehensive action plan to significantly enhance this area over the coming years.

Rocrail

Main article: 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.

External links

• DCCWiki - Community DCC site for model railroad.
• YouTube - Railmaster video on YouTube.
• Hornby - RailMaster site at Hornby.