DCC Information

This section is dedicated to all aspects of DCC, Digital Command Control.

Our Own Lenz System

The MCMR layout is controlled by a Lenz DCC Command Station along with Lenz LH-100 controllers.  The link below will direct you to the LH-100 Manual so that you can refer to at a leisurely pace from home.  Here's the link:


How to Reset a Decoder

Caution! While as accurate as possible, the use these instructions is at your own risk!

Sometimes locomotives act strangely or stop working all together. The big fear is that the microprocessor that operates the loco, aka the decoder, has been electrically fried. Here's what Tony's Trains has to say about this:

"The ability to change a decoders CV settings gives an engine a multitude of customized features. Many modelers only go as far as changing the decoder’s default address from 3 to the cab number. A common fear is that if you enter the wrong value, lose control, you may end up in limbo without the ability to recover or correct the problem. Also, sometimes a track short circuit may cause some decoders to get corrupted and not respond correctly. Good news! There is generally a simple solution. Most decoders have a way to restore the decoder CVs back to factory default settings ... much simpler than trying to figure out which CV was causing the problem!

According to the manufacturers, many of the decoders returned for repair could have been rescued if they had been first reset to factory settings. I talked with one decoder manufacturer who said at least 33% of their returned decoders are “fixed” by using the simple reset procedure."

Generally  speaking, resetting a decoder means entering a certain value into CV-8, where the decoder manufacturer's ID# resides. If you have the decoder's documentation, then following the reset directions in it is the ideal way to proceed.

Without documentation, we don't know what's under the hood and so we proceed as follows:

First, place the loco onto the programming track. Reset can be accomplished on the normal operations track (programming on the main) but if one is not expert at this procedure, use the programming track. Also, apparently the Lenz system only allows reading of a CV while in program track mode.

Second, use the Lenz LH-100 controller, Function 8, to read CV-8 to learn the decoder's manufacturer code number.  Also, there is an index card file in the work bench area of the club that, for most of our locomotives, contains the name of the installed decoder as well as some of its initial CV values.

Third, follow the directions below. (These directions and the table came from this website, http://sdrmweb.co.uk/media/CV8.pdf which is among the clearest that could be found.)

CV 8 – Popular decoder manufacturer’s ID codes (for others, search the internet)


ID code in CV 8

CV to reset (and value to enter)



CV 8 = 8 (or 33)





CV 8 = 8



CV 8 = 33




CV 30 = 2




CV 8 = 8

LokSound (ESU)


CV 8 = 8*


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CV 8 = 8

How to reset a decoder

Writing a new number to CV 8 will not change the value in CV 8 when you read it back, but it will reset the decoder to the manufacturer’s original settings.

Always read the manufacturer’s instructions before attempting a decoder reset!

*Caution - Resetting CV 8 may delete your sound files! 

Also remember, resetting a decoder will change the address back to the default of 03.

On the program track read CV 8. Compare the number with the above chart for the ID and then write to the matching CV the value as shown in the chart. When resetting the decoder, it may respond by flashing the lights or sounding the horn. 

Finally, what if the above doesn't work? It could mean a loose or disconnected wire or an unseated chip inside the loco that needs to be found. Or it may mean that a new decoder is needed.  That is really not an end of the world problem. In fact, one might be inclined to add an even newer decoder with more options and possibly on-board sound.





  1. I’m adding my own comment today, March 4, 2014. At the club today, I thought I would start to use this information, on the Program Track, to reset a couple of locomotives from the bench that had become unresponsive. I learned that you can’t get to second base until you reach first base, um, first.

    First, one needs to understand the Club’s Program Track set up. A Program Track needs to be electrically isolated from the other tracks. On the Club’s layout, I see THREE switches for Program mode: One under the table in the center near the main power switches to the districts. Its marked Program or Normal; the next is at the end of the layout where the program track is. It’s the box that gives a choice between Off, DC, DCC, and PROGRAM ; the third switch is right in the same area. Its called BPX or BBX or something, a programming little black box.

    So… which way do we activate our programming track so that when we program on the Program Track, we don’t inadvertently mess up any other loco? Do any old timers remember?

    Bill Flanagan

  2. The switch near the main power puts the Lenz system in programming mode. The system will not run trains while in this mode. The switch near the programming track is used to isolate it from the rest of the layout (and thus prevent affecting any other loco decoders). The BBX (Black Box) can be used to program decoders separately from the Lenz system. The switch near the main power does not need to be used for this. The BBX has a separate jack to plug in a controller. The BBX does not have enough power to run the loco and therefore can not be used to test if the programming was successful. That can be accomplished by switching the test track to DCC (and using a different jack for the controller).

    Larry McCarthy

    • Thanks Larry, that information is very helpful. And, as you know, we successfully read cv’s using the BBX method. It’s my understanding that by providing less power, the BBX program track helps prevent shorts if a new controller were inadvertently wired incorrectly.

      Bill Flanagan

  3. The DCC system went from Lenz to MRC to Digitrax. This section needs to be updated, 5/12/21

  4. The HO and N scale layouts use DIGITRAX DCS 240’s with UT6D and DT602D throttles. HO layout has WIFI access for cell phone operation.

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