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Triple Header and Test Track

The reason I can triple head engines is that I use
Speed Tables in the Digital Decoders.

My friend Phil developed a script which runs on Decoder Pro that will automatically create the speed tables. We may be the only folks in the country or world doing this at the moment.
This is my test track (above) for both N scale (in which I model) and HO for my friends. It features a Digirax Zephyr command station. The circle of track has 16 equal length blocks each detected with a Digitrax BDL162 feeding back into the loconet, a programming track, Locobuffer which connects the loconet to the PC and Laptop with JMRI Decoder Pro installed.

Phil made a script which we have set up to run in the Decoder Pro and, after initialization, I enter the road number, decoder type, and scale, and hit start. The engine first does 5 warm up laps in both directions, tests for decoder type (Digitrax, NCE, Lenz, TCS, etc) and then proceeds to build the speed tables for various throttle settings based upon internal script tables figured out earlier for each type of decoder.

As each engine traverses from one block to the next, the script measures the time between blocks and uses that to calculate scale speed. It takes 5 different readings, averages and throws out any outlyers, then compares the speed to the target speed and adjusts the throttle up or down to get closer to the target speed.

For instance, it begins with 10 MPH and works the throttle settings to fine tune with in a very close margin which throttle setting makes the engine run at 10 MPH, then it goes to 22 mph (in the case of Digitrax) and finds the throtttle setting, etc. It keeps going to build the compete curve. The average amount of time per engine, so far to run the program is about 12-15 minutes but I have had engines take 30 minutes to run the whole program.

The end result is that all engines run in a similar speed pattern and I theoretically can mix and match engines. Still needs more fine tuning but it seems to work pretty well.

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Reader Comments (10)

Kent - You and your neat digital toys never cease to amaze me. Bruce's tried to get me to buy the Prodigy DCC, but I relented because I was unsure of Loconet compatibility. Having _no_ luck finding the Digitrax Zephyr. Might be online time unfortunately for Railroad Hobbies.

March 14, 2006 | Unregistered CommenterDustin

Phil, would you be willing to share that script to do the speed tables??


April 26, 2006 | Unregistered CommenterPhil Utley

The author of the script is Phil Klein. He might be willing to share it. Post another comment with your email address (which I will edit out of page but then use to send you an offline email with his address.--Kent

April 26, 2006 | Unregistered CommenterKent at Ananda Village

That's a pretty neat way of setting speed tables. You'll have to keep posting in your blog as things progress. Thanks for the info and great website.


February 1, 2007 | Unregistered CommenterAnonymous

Being new to DCC I would like to build one of the speed tracks, would it be possible to find out exactly what you used to build yours? I would like to be able to use different Locos together but at present am having a hard time getting them speed matched.

Thanks Brian

April 27, 2008 | Unregistered CommenterAnonymous

back to Brian--the script and instructions are on the JMRI yahoo groups site files--KEW

April 28, 2008 | Unregistered CommenterKent at Ananda Village

The speed curve system is good and needed.

There is a new model railroad product, RPS ( that measures position anytime and anyplace using ultrasonics. An RPS equiped car the RPS base stationa and one receiver could provide the needed information for a driving locomotive is a few feet of straight track in a few seconds.

What is available, a JMRI script, instructions?


May 24, 2008 | Unregistered Commenterwjnaumann

Walter- I think Phil has published this script on the JMRI site in files. You could post on JMRI yahoo group and they would know--Kent

Phil - I just downloaded your script for the speed table. I have used Decoder Pro in the past only to program decoders. This is the first script/panel that I have ever run. Can you please tell me how do I start? Where do I put the script and the graphics and how do I launch it? Any help you can give will be greatly appreciated. thanks, Bobu.

January 14, 2009 | Unregistered CommenterAnonymous

answer to your question:
In DecoderPro, click on “Panel”. Next select “Load Panel”. To run the script , click on “Panel” again and select “Run Script”.

You can save the files anywhere you want, and change the extensions if you choose.

January 15, 2009 | Unregistered CommenterKent at Ananda Village

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