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The WiThrottle System



This page was last updated on October 26th, 2012.




WiThrottle is a service that is a standard part of the popular open source JMRI software used for model railroading. You may know it better as "Decoder Pro". It allows any model railway connected to a computer to a wifi network to receive wireless signals and run operations on a model railway. Smart phones and wireless devices can give commands.

Simply put, it's a simple, cheap and effective way to turn your phone or tablet into a high end multi-function throttle.

What do I need?

For HOTRAK, all you'll need is a compatible wireless device. If you want to set up a system at home, consult the web pages listed at the bottom or ask a member of the club who have set it up themselves.

  • Any iOS device - Apple iPhone, iPad or iPod Touch
  • Any Android device (smart phone or tablet) that can install application from Android Market

How to set up

  • For iOS devices. Simply open up the App Store and search for "WiThrottle", install 'WiThrottle Lite' for free (if you like WiThrottle', you can install the full version for $9.99 which includes consisting)
  • For Android, got to Android Market in your device and search for 'engine driver' and install. Engine Driver is completely free and open source.


When you arrive at HOTrak, open up the wifi settings on your phone or tablet and select the aptly named 'HOTrak' network. Once you are joined onto the network open up WiThrottle or Engine Driver and select the server.  When you start the throttle the name that comes up is the name of the computer that is running the JMRI software and the IP address of that computer. The IP address changes each time the system is started since it is assigned by the router.

Running trains

Be warned, the throttles may seem overly intuitive to those used to DigiTrax throttles. It is easy to consist locomotives and you don't have to plug in at all.  However, this can be hard on battery life and you may need to carry a spare battery or bring your charger to top off the device while taking a break.

  • For WiThrottle on iOS simply hit the 'keypad' option and type in the address of the loco you wish to acquire. Scrolling left to right to find extra functions. Screenshots with explanations can be found here: http://www.withrottle.com/WiThrottle/Images.html
  • For Engine Driver - On the throttle screen, click on the "Press to Select" loco button for each loco. On the next screen, enter the loco address (verify short or long), and press "Acquire".  You will be returned to the Throttle screen. Operate your loco using the slider for speed, and the reverse, stop and forward buttons to control direction."http://jmri.org/help/en/package/jmri/jmrit/withrottle/EngineDriverAndroidThrottle.shtml

More reading:

WiThrottle Overview at JMRI: 

http://jmri.sourceforge.net/help/en/package/jmri/jmrit/withrottle/UserInterface.shtml

WiThrottle host requirement checklist:

http://www.withrottle.com/WiThrottle/Can_I_Use_It.html