LocoNet Interfaces

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Summary: Computer interfaces available for LocoNet

To communicate between a computer and the LocoNet, you need a translator that will understand both of them. Interfaces are available from both Digitrax and third-party vendors.

Interfaces allow the use of software running on a computer to configure various devices, as well as programming locomotives and other decoders.

Interface Devices


The current Digitrax solution is the PR4

  • PR4 / PR4 Xtra
  • Multifunction USB to LocoNet connectivity.
  • MS100 - Digitrax's own computer/Loconet interface device.
    • Has been significantly outdated by the LocoBuffer II
    • Connects via RS-232. Some users report RS-232 <-> USB adapters work.
    • It has now been discontinued. Its replacement is the PR3.
  • PR3
    • Discontinued
    • Replacement for MS100
    • Uses USB-2.0 for connection to computer.

Third Party Devices


  • LocoBuffer-NG (Next Generation)
    • RR-CirKits
    • Replacement for the LocoBuffer-USB
    • LocoNet® to USB [1] Interface
    • 1.5kV isolation between LocoNet and USB port
    • Type A* USB connector
    • Powered directly from LocoNet and USB [2] [3]
Older LocoBuffer Versions
  • LocoBuffer - Third party hardware interface device
    • Developed by John Jabour in response to speed and platform restrictions of the MS100. Technically was not much better than the MS100
    • Was available in complete or kit form from the designer until he decided not to make them available any more.
    • Manufacturing of the unit to was transferred to RRCircuits.
    • Original LocoBuffer is no longer available.
  • LocoBuffer II - Developed by RR-CirKits as a replacement to the original LocoBuffer. (Out of Production)
    • Faster, smaller, and more up to date.
    • Certified by Digitax
    • Connects via RS-232. Many users report RS-232 <-> USB adapters work well.
    • Faster serial connection, fewer dropped packets.
  • LocoBuffer-USB - Developed by RR-CirKits as a replacement to the LocoBuffer II (Out of Production)
    • Replaces LocoBuffer II
    • Connects directly to USB port
    • Powered from USB connection and Rail Sync lines, no external power supply needed.


  • LNGateway - Opensource Arduino based DIY interface device
    • Connects via USB
    • Opto isolated, powered by USB and Rail Sync lines
    • Intended to be used together with JMRI as low-cost solution for connecting WiFi throttles
    • Circuit design files and source code available on the LNGateway Github pages


Digitrax MS100

  • DB-25 serial RS-232 input
Obsolete. Originally released in 1996.

From the Digitrax Website:

The MS100 Computer Interface is designed to let an IBM compatible computer with RS232 communications port monitor Digitrax LocoNet. The MS100 is a signal level translator between LocoNet and a 25 pin DB25 style RS-232 port. It is basically a dongle that plugs into the 25 pin RS-232 serial port, with an additional cable connecting to LocoNet.

Application software running in the computer can then interpret the activity on the LocoNet and report back to the user via the computer screen. The interface was primitive, passing all messages to the computer, which results in additional overhead.

Digitrax PR4

The PR4 supersedes the PR3. The PR4 has been replaced by the PR4 Xtra, essentailly the same device now with a power supply included

  • Multifunction USB to LocoNet.
  • Optimized for Direct mode
  • LocoNet is Electrically Isolated from USB port.
  • “SoundLoader” decoder compatible.
  • Programs most DCC decoders.
  • Standalone operation: No requirement for a Digitrax Command Station.
  • LED status lights.
  • Opto-isolated.

Works with Mac and MS Operating Systems. PR4 software is MSWindows only, JMRI compatible (MacOS).

(Dec. 2017)

Digitrax PR3

  • USB-2.0 input
  • May be used with Digitrax' "Soundloader" program (currently Windows only).
  • Compatible with Windows 2000, XP, and Vista (Windows 7 status currently unknown)
  • Compatible with JMRI on Mac OS 10.4/10.5 and Xubuntu 10.10
  • Only requires a power supply for use with "Soundloader" program.
  • LocoNet® terminator included.
  • Software configured
  • Not Opto-isolated.

Third Party Devices


LocoBuffer II

LocoBuffer-II specs:

  • DB-9 serial RS-232 input
  • Opto isolation (if not using LocoNet® powered mode)
  • Buffered input and output allows use with all operating systems. (Linux, Mac, MS Windows)
  • Hardware handshaking using RTS/CTS (also includes DTR/DSR turnback required for MS Windows XP)
  • Packaged unit size 1-1/2" x 3-3/4" x 3/4"
  • Ready To Run
  • Optional Package available with cables, (DB-9 or Mac DIN-8, and 14' LocoNet®) plus 9V power supply
  • LocoNet® terminator included. Rev-f terminator is built in. (Allows you to use your LocoBuffer-II to add LocoNet® device compatibility to other systems)
  • DIP switch settings for all options
  • MS-100 compatible plus 19,200 and 57,600 standard Baud rates
  • Serial Boot Loader programmable for upgrades (Does not require special hardware)
  • Power from 9V-12V AC-DC
  • Optionally LocoNet® powered from rail sync lines
  • Digitrax LocoNet® certified.
  • Suggested Retail Price: $69.95.

LocoBuffer-USB Features:

  • USB 2.0 to LocoNet® interface
  • Optical isolation between USB and LocoNet® prevents potential grounding problems
  • Buffered inputs and outputs allow use with all USB supported operating systems
    • CD with drivers for Linux 2.4, Mac OS-9, OS X, MS Windows 98SE, ME, 2K, XP
  • Packaged unit size just 1-1/2" x 3" x 3/4"
  • Ready to run unit
  • Internal LocoNet® terminator.
    • Allows a LocoBuffer-USB to add LocoNet® device compatibility to other systems
  • 57,600 Baud interface speed
    • No jumpers or switches to set
  • Compatible with existing software
  • Installs as a serial port
  • Hardware handshaking using RTS/CTS
    • Includes DTR/DSR turn back required by MS Windows XP
  • Boot Loader for firmware upgrades
    • Does not require special hardware to install upgrades
  • Powered directly from USB and LocoNet® Rail Sync lines
    • No external power adapter needed
  • Internal option connector allows for future features
    • Planned optional programming track output
  • Includes 3' USB A-B and 14' LocoNet® cables
  • Suggested Retail Price: $ 74.95

LocoNet USB Interface 63120 by Uhlenbrock

The USB-LocoNet Interface build by Uhlenbrock Elektronik GmbH offers a number of advantages. As with the LocoBuffer-USB, it uses a microcontroller for precise LocoNet timing, reducing the load on the computer.

  • Opto-isolated
  • Modes:
    • LocoNet Direct
    • Only valid LocoNet messages are passed to the computer

L.Net Converter - ESU

ESU has added the L Net Converter or ECoS Throttle Integration Adapter.

It will allow connection of LocoNet throttles to an ESU command station such as the ECos. This will allow you to keep your existing LocoNet devices, such as feedback modules, as well as your Uhlenbrock or Digitrax throttles.

This device works with the ECos or the older Central Station (60212) command stations.

Feedback Modules

Loconet modules such as those for track occupancy detection. The L.Net Converter allows those devices to connect to the ECoS, for activating routes or shuttle train control. Use of s88, Loconet and ECoSDetector feedback modules is possible at the same time.


The L.Net Converter solves the communications problem: the ECoS will send loco and turnout commands via the L.Net Converter to the devices connected.

Ethernet to LocoNet

  • Ethernet to LocoNet interface with integrated Power supply.
  • Optical isolation between computer and LocoNet.
  • Running with Rocrail
  • Do It yourself package or Pcboard is available
  • IP adress selectable via EEprom settings
  • Suggested package price €65,-- , pcboard only €9,--
  • Pcboard is double sided with silkscreen and solder mask. Through hole connected.
  • Rocrail.net

Do It Yourself Solutions for LocoNet Interfaces

A few solutions exist for "roll your own" interfaces.


LocoLinx on Arduino UNO with FremoLNShield

Supports Hardware Handshaking. Requires a LocoNet Shield

Webpage with more information.

LocoLinx on Arduino Duemilanove with Loconet Shield on Proto Shield

This one is outdated and may be difficult for find

Suports hardware handshaking via the CTS line. Incorporates a genuine FTDI USB IC, less issues with drivers. (The LocoBuffer USB also uses this IC.) Duemilanov

Webpage with more information.

There is more information on LocoNet interfaces available on the LocoNet over TCP webpage.

ArLoco from ARCOMORA

The ArLoco is an Arduino Shield 16 (UNO) or 58 (MEGA2560) channel feedback encoder with LocoNet interface.

Supports LocoNet-T and LocoNet-B. Has two LocoNet RJ12 jacks.

For more information see their website.

Model Railroading with Arduino LocoNet Interface

This site has details on a LocoNet interface. Construction details are here.

There are a number of other projects on that site as well.

Iowa Scaled Engineering

DCC Decoder Shield for Arduino

The ARD-DCCSHIELD is an optoisolated interface shield for connecting an Arduino (as a decoder) to a model railroad DCC control system. It cannot act as a command station.

NMRA Digital Command Control (DCC) Library

This library allows you to interface to a NMRA DCC track signal and receive DCC commands.

The library currently supports the AVR ATTiny84/85 & ATMega88/168/328/32u4 and Teensy 3.x using the INT0/1 Hardware Interrupt and micros() ONLY and no longer uses Timer0 Compare Match B, which makes it much more portable to other platforms.

Download the NMRADCC library from GitHub.

  1. Uses aType A connection
  2. Uses RailSync power (10 mA load)
  3. May require a USB Type C Male to USB Type A Female adapter cable.