DCC combined with Computer Control

Question: I have spent quite a bit of money on my DCC  layout only to discover that Computer Control via my PC would be the next logical step for me. I would like to incorporate Computer Control without abandoning my DCC hardware. Do you have any suggestions?  Mel, New York City

Over the past few years Computer Control of model railroads has been developed, particularly the Digital Command and Control (DCC) type.  The following paragraphs discuss Computer Control techniques from various manufacturers:

o CTI Electronics


o Digitrax

CTI Electronics of Baltimore, MD is a developer of model train Computer Control software (not free) and associated interface hardware  that will permit your DCC model train layout  to run your trains and associated model railroad accessories using an IBM Compatible Personal Computer (PC).  Basically with the CTI scheme your present manually operated control panel is replaced with your PC screen.

Of course your PC screen with the help of CTI software and an array of  hardware control and sensor modules which  CTI refers to as Train Brains becomes a rather sophisticated train control panel. Each CTI electronics Train Brain is daisy chained into a communications network which is connected to your computer’s COM or USB port.   See Figure below.

With the Train Brains it will be possible to control various railroad functions turnout control, track signal control,  detect and display train position, and detect and display turnout position, just to name a few.  In addition there will be true interaction between track signals, train speed and direction providing true model train speed control.

Train Brain sensor modules are compatible with various types of sensor components such as Infra-Red, Photo cell and Current Detection.

The CTI Smart Cab Hardware Module provides a pop-up throttle display onto your PC screen integrated with other Train Brains effects in lieu of using your own  DCC controller (Throttle). Effectively will you will have accomplished the building of your own model railroad DCC controller.

If you have a DC layout with blocks that are used to operate more than one train on a track, also lends itself control via the CTI Smart Cab Module.

You can also use your own DCC throttle for parts of your layout operation and Smart Cab for the remaining sections.

In other words, use your DCC throttle without Smart cab and limit your Train Brains for turnout control, etc. for semi-automatic operations. Again the computer will interface with the model railroad turnouts using the USB or COM ports.

Visit the CTI website for additional and more detailed info.

To date, CTI Electronics software supports the following DCC controllers:

o   Power House Pro and Power Cab series from North Coast Engineering (NCE)

o   System One from Wangrow Electronics

o   DCS-100 and Zephyr from Digitrax

o   Easy-DCC system from CVC

o   XPress Net from Lenz

o   V2x- Bus based on command stations from Lenz

o   Master command station from ATLAS

o   Train Master Command Control (TMCC) from Lionel

o   Marklin Digital System from Marklin

It is also possible to mix CTI hardware and software with other vendors.

Visit the CTI Electronics site for additional information.


JMRI which stands for JAVA Model Railroad Interface is Freeware comprised of the following applications:

o JMRI DecoderPro

o JMRI PanelPro

o JMRI Tools

o JMRI LocoNet Tools

JMRI DecoderPro

DecoderPro software is free and is compatible with the following operating systems: Windows, Linux, Macintosh (OS 8.6 through 9.2 and MacOS X), and OS/2.

JAVA must also be available as well as a serial interface, either on the computer itself, or via a USB adapter.  You also need to have a serial connection to your DCC system for your DCC computer interface. For more information, reference the DCC hardware pages on the JMRI website.

DecoderPro performs the following functions and provides the following attributes:

Programs Configuration Variables (CVs) into a locomotive’s decoder without using your own DCC command station. Can also be used to program stationary decoders. Much more user friendly than typical DCC command station.

Configured using text files, can be adapted to additional decoder types.

Create a Roster of every locomotive you have depicting detailed Configuration Information for the installed mobile decoder.

Communicates to decoders using JMRI programming interface, compatible with most computers and layout hardware.

Open Source code, can be changed.

JMRI PanelPro

Panel Pro performs the following functions and provides the following attributes:

It is used to create front panels on your PC screen. This is accomplished in two ways:

o  Panel Editor will allow you to make a drawing of your track layout with icons representing turnouts, etc.

o Layout Editor will allow you to develop the logic for the icons, such as turnout position appearing when icon is clicked upon.

Other Handy JMRI Tools

SENSORS – Tool permits interface with your layout’s sensors to provide the sensor’s output, for example train position to be displayed on replica of track layout on PC screen. Other items like semaphore operation is another item that can be displayed.

TURNOUTS – Used to control and display  turnout position via PC screen, on track replica or used for semaphore operation, etc.

THROTTLE – Used to create a graphical throttle interface on PC screen.

CONSISTING –  Used to control more than one locomotive to pull the same train.

SIGNALS – Provides signal head control, lamp colors as a function of train occupancy detection sensors, train speed, etc.

LIGHTS – Provides lighting for control panels as well as scenery.

ROUTES– Permits the development of canned program scenarios to set up a complete set of actions and reactions on a train layout by one command, such as turnout control, in addition to others.

LROUTES – This tool is an extension of the ROUTES tool to include lights and signal heads.

LOGIX – Permits the model railroad hobbyist to set up logical conditions on the layout.  For example, train direction and presence using model train block occupancy must be detected prior to operating a crossing gate.  The tool is user friendly. The need for expressing himself with mathematical terms is not required.

FAST CLOCKS – Fast Clocks are used in model railroading to simulate the faster passage of time which makes the train on the layout appear to run longer distances.  In particular, this tool develops an internal fast clock using your computer or it can interface with an external clock provided by other DCC system vendors such as Digitrax or NCE.

SPEEDOMETER – The tool calculates and displays the train’s scale speed.  Of course it is based on the train being detected as it passes motion sensors.

ENGINE SPEED MATCHING – Used as part of the Consisting process previously mentioned.

SCRIPTING – In the world of computer programming, a script is a program or sequence of instructions that is interpreted or carried out using another program rather than the computer processor, (as a compiled program is).  JMRI scripts use Python, a popular general-purpose computer language, which will be used to control the model trains.

AUDIO – This tool controls sounds that are played back by your PC.

ID TAGS – This tool creates Identification Tags (ID Tags) for many items on your layout, for example, rolling stock.  With the use of sensors the tool can track rolling stock position and report the time the stock was last observed.

LocoNet Tools – These tools have specifically written to interface with the Digitrax LocoNet specific hardware devices such as the PR3 which will tie in to the computer via the USB  interface port  to the Digitrax DCC model train controller.

The purpose of the above explanations was to give you an idea of the JMRI tool suite. More detailed information is available on the JMRI website.


Digitrax manufactures the following hardware products that are used for computer control:

MS1oo is a RS232 Computer Interface device

The PR2 is an interface device which allows Digitrax SoundFX locomotive decoder users to download new Project sound files and even reflash the decoder’s firmware for latest updates.

The PR3  is also an interface device but is different from the PR2 in that it offers a USB 2.0 interface,  selectable MS100 mode, and is priced lower.


  • The MS100 Computer Interface allows computer with an IBM compatible COM, or RS232 communications port, to monitor Digitrax LocoNet.


  • See Figure below:

  • For example, an application from either CTI Electronics or JMRI Panel Pro would display a control panel to include a replica of the railroad layout on the computer screen. The software messages received via LocoNet and the MS100 will indicate block occupancy, signal state and other information generated by detection devices attached to LocoNet port. This is how the DCC system can detect train location.
  • Ofcourse the programming details can be found on the CTI Electronics website or JMRI website.
  • For IBM compatibles with only a 9 pin male DB9 type COM port connector, you can use a DB9(female) to DB25(male) adapter commonly sold in electronics.  Make sure you are connected to the correct COM port and that you have it set up as required to match the settings needed by your CTI Electronics software.
  • For the latest Computers which have a USB Interface another type of adapter is required. Ses figure below.

PR2 SoundFX Decoder Programmer performs the following functions:

In conjunction with SoundLoader software the PR2 allows the hobbyist to substitute different locomotive sounds into a Sound Project file.

Digitrax also has a website (Digitrax Sound Depot) which can be used to download Sound Projects.  Your Sound Projects can also be uploaded to other model train hobbyists.  Link to the Digitrax Sound Depot for more detailed information.

See Figure below:

There is an alternative hook-up for the PR2 which uses a USB port adapter if required. See following Figure:

 The PR3 is slightly different than the PR2 in that it is compatible with a USB 2.0 interface, has a selectable MS100 mode and is priced lower than the PR2.  The PR3 also provides the USB/LocoNet connectivity for third party software such as JMRI, Railroad and Co., and others.  See Figure below:

Here is another device that is good for third party software usage. It is called the Loco Buffer-USB and is another way to interface between a Digitrax DCC Controller and a Computer’s USB port.

It is manufactured by RR CirKits, Inc. 7918 Royal Ct. Waxhaw, NC 28173

See figure below for typical hook-up.


 Reference to link for hardware and software compatibility.

The previous scheme can be expanded to include the addition of  CTI hardware and software for control of a typical group of  CTI’s Brain Train devices. See figure below.

If you wish to acquire a better understanding of Electronics Theory, I suggest you go to  the following  link: Electronics