Programming Decoders

Basic Programming

The Digitrax PR-1 decoder programmer is a bear to get to work. The challenges were many, but here is the final configuration that made this picky device and software work:

Previous failed attempts included using my main desktop machine with a 18V custom-built power supply using the WinPR1 software program. This didn't even detect the PR-1 device hooked-up to the machine's serial port. I since then learned that the older the PC, the better the success rate. I dusted off the old 8088, but then I re-acquired my old laptop computer. The laptop is definitely more portable and convenient, especially since space in the model railroad room is at a premium. Here's a photo of the setup used to program the locomotives' decoders.

More Advanced Programming

To be able to program the new sound decoders, the basic set-up just won't do. The Digitrax Command Station doesn't provide enough power to the programming track to be able to correctly communicate with the decoder. However, there is a reason why Digitrax did that. If you wired the decoder such that there is an accidental short, applying full power to the decoder while programming it could instantly fry the decoder.

The photo below is of the Soundtraxx PTB-100, which is a programming track booster. It is specifically designed to be used with programming sound decoders, however, non-sound decoders can be programmed with it as well. The instructions that come with the unit are pretty easy to follow. It provides more power to the programming track, but it also provides protection in case of short-circuits created during the decoder installation.

Programming in Style


- Locobuffer USB package -

The ultimate in programming the decoders in our locomotives is to be able to do so using our computers. However, to be able to do that, there must be a way for the computer to communicate with the Digitrax Command Station (or any other DCC system for that matter). There is also a software component, but I will get to that shortly.

RR-CirKits has been manufacturing a product called "Locobuffer" for several years now. This piece of hardware makes it possible to establish communications between a computer and the DCC command station.

I bought their Locobuffer USB package, because most modern computers now use USB for externally connecting devices. The package comes with the Locobuffer device, a RJ-12 6-wire telephone cable, a 3-foot USB 2.0 cable, and a CD-ROM containing the device driver for the various supported computer operating systems and the JMRI and RR&Co software (demo version only). This large collection of parts is shown in the photo below.

My laptop has Windows Vista Home Premium 64bit installed on it, so I needed to download the drivers from the RR-CitKits web site, because Vista didn't like the ones provided on the CD-ROM. The screenshots shown on the RR-CirKits' web site are pretty accurate and very helpful in getting you started. Installing the drivers was fairly straight-forward once I had them downloaded from their web site.

To actually communicate with the layout and its attached decoders, you will need to download the JMRI (Java Model Railroad Interface). This will also install DecoderPro (used to program decoders) and PanelPro (used to control turnouts, etc. on the layout). Again, these are available on the CD-ROM, but if you have an Internet connection, it is much better to download the latest version from the web site rather than some, potentially, outdated version on the CD-ROM. I presume that the CD-ROM was provided for those who do not have an Internet connection.

Current Setup

For my current layout I have a section of track, about the length of my longest engine, that can function as the programming track. The diagram below shows my entire set-up. The Digitrax command station's programming output is connected to the Soundtraxx PTB-100 programming track booster. This programming feed is connected to one pole of the double-pole/double-toggle switch that selects whether the isolated section of track is powered by the standard DCC track power or by the programming feed. The laptop with DecoderPro is connected via the Locobuffer II to Digitrax' Loconet.

Note that for Soundtraxx decoders, when they are being written to by the programmer, they cause the engine to move slightly forward for each write to the CVs. This is to acknowledge the writing, but it does require a bit of a longer programming track than just the length of the longest engine.

The next set of photos shows the construction of the programming track on my current S-scale layout. I laid the regular track up to the point of where the insulated section of track was to be on this spur. I had previously marked off on the edge of the subroadbed where the programming track was to be, because I wanted to remember to stop laying the track at that spot.

I cut two small 0.020" styrene pieces and superglued them to the end of the rails (if you look closely you can see them). Next, I did my normal track laying step to get the two rails in place. The next photo shows these two rails ready to be installed. I used a different feeder wire color so as to distinguish these from the other feeders.

After the rails were installed, I trimmed the styrene pieces to match the rails. I temporarily connected the red wires to the DCC bus so that I could test the track. I then went and built a utility panel that houses the programming-or-track switch to which these red wires are connected. The next photo shows an engine on the programming track.

Conclusion

It is now trivial to drive the engine onto the programming track, flip a switch, do the programming, flip the switch back, and I'm up and running again. Connecting my laptop to the DCC system is trivial too, with my new utility panel. DecoderPro makes it easy to program the decoder. I did have to use the online manual for DecoderPro, because the application is not intuitive to use unless you've been working in it for a while.

References