4 digit addressing problem

greenspun.com : LUSENET : Wiring for DCC : One Thread

I have a Digitrax Chief and recently had the opportunity to use it alongside a System One. We used locos programmed on each system with the other, generally with no difficulty. However, one problem did turn up. One of the locomotives is road number 106 and the owner had programmed it for a long address of 0106 on his System One. He retains the default short address of 03 for all his decoders and runs all his locos with long addresses.

The problem is that when I tried to address that loco with my Chief, I could not. As far as I can tell, the only way to address locos with an address of 99 thru 127 is to use the hex to dec mixed mode addressing which is interpreted by the system as a short address.

Have I overlooked something here? Or is this really a restriction in the Digitrax implementation?

It seems to me that there is no real reason for this restriction, at least in the Chief system. Since I need a DT100 to use even the mixed mode address range of 99 to 127, it should be possible to set any address I want as a long address.

I haven't tried it but my guess is that I cannot program or select a long address of 0127 or less. I think that is a needless restriction in the Chief system too if it is true.

Dale Gloer

-- Dale Gloer (dgloer@ca.ibm.com), November 08, 1999



I was had by this Digitrax shortcoming a few months. Logically, there is no reason for Digitrax to retain this shortcoming. Certainly, I was doing something wrong. Nope. I checked with AJ. Addresses that can be represented by short addresses can only be represented by short addresses.

Addresses that fall into that no-man's land of "deci-hex", or whatever they call it, are eternally cursed. I can do hexadecimal (note: Digitrax's creative display is not hexadecimal) addition in my head, so you wouldn't think I'd be complaining about it. But I think it is definitely a detriment to sales. The average modeler should not have to deal with this when there is no technical or cost impacting reason. It definitely supports the notion that Digitrax throttles are hard to use.

Once I confirmed that I must live with it, I read up on it. Fortunately, I found that it wasn't painful. Take that with a grain of salt from someone who can do hexadecimal math in his head!

-- Allan Gartner (wirefordcc@augustmail.com), November 08, 1999.


It is true, but it is only from 100 to 127, not 99, that is a short address direct. The Digitrax range for short addressing is 00 to c7, and the long address range is 0128 to 9980.

And no c7 is not hex but a simple form of alphanumeric to allow 3 digits to be used in a two digit space. It is really pretty easy to understand, A=10, B=11, C=12, and just include the second digit. Thus in your example 106 = A6 or 127 = C7.

Some feel this is a restriction, and it can be looked at this way, but there is a logic to the madness, that is compatablity.

The DT200 throttles and the Big Boy only allowed short addressing, and the DT200 only had room for 2 digits in the address, thus the alphanumerics to get 100 to 127, the short address limits into the display. Then along comes long addressing, and shortly later the Chief, to maintain compatablity with the Big Boy, and more so that the DT200 throttles could be used on the Big Boy, they still maintain the 00 to C7 short addressing limits.

And some feel this is pain, and others do not seem to mind it. My self I had a Big Boy for as long as it was out, till the Chief came out then I moved up to it, so the A0 to C7 never bothered me, and I just learned that A=10, B=11, C=12, and do it second nature anymore.

Most all systems limit short addressing to 00 to 127, and if one programs C7 on a Digitrax system, it will show as short address 127 on others, and the same the other way around. The only real difference is other systems with long addressing will long address from 0001 to 9000+ thus the long address will over ride the short all the way down to 0001. Digitrax could have easily done the same, but doing so would have cut all Big Boy users out of the loop so to speak, and the DT200 throttles would have been useless on the Chief, Empire Builder, or Genesis. As it worked out all my DT200's are still in use today on my Chief. So I am glad they did it that way.

May not be the best solution or what ever, but on the same note it really is not a needless restriction either. Maintaining compatablity may not always be a good thing, unless you happen to be one like me that did and those that still do today have one of the older systems.

Remember Always Have Fun and Enjoy!, Don Crano Akron, Oh NMRA #096211 mailto:donc@sssnet.com Visit Model Railroading with DCC at: http://pages.sssnet.com/donc/

-- Don Crano (donc@sssnet.com), November 09, 1999.

Thanks to Don and Allan for confirming that the restriction is real.

For me downward Digitrax compatibility is not the issue, cross vendor compatibility is. On that point Digitrax is deficient. It seems to me that some programming could take care of this. I hope Digitrax is listening.

-- Dale Gloer (dgloer@ca.ibm.com), November 09, 1999.

Moderation questions? read the FAQ