Good morning everyone,
I know these are most likely going to be lame questions, but I have to ask, because I just don't know anything about CV's (1) Why are CV's not already programed into a decoder? (2) Once the CV's are set, or programed in a loco, what are the reasons why you might want to change them? (3) If the CV's were programed with one DCC system, Will the loco follow the same commands when using a different DCC system?
Thanks to all,
Sam
1. CVs (Configuration Variables) are pre-programmed into a decoder.
2. Not all CVs are set to the proper value for a particular application, so one or more may need to be changed. Example: If you change from a short address (default of 3) to a long address (a locomotive number that is higher than 128) you have to change the value in CV29 to tell the decoder to use the new address.)
3. Yes, all DCC systems will run a decoder-equipped locomotive exactly the same as long as you have the correct address entered and the DCC system is capable of supporting the various functions (lights, sounds, etc.)
4. Decoders come from the factory set to address 3 and the headlight and backup light (if there is one) set to be on according to the direction of travel. A CV can be reset to have the headlight stay on when backing up, which is how real trains operate.
Practically every decoder brand and type comes packaged with a list of factory set CVs indicating what each one does. If you need to access more than those enclosed with the decoder, you can usually download a "Technical Reference Manual" from the manufacturer's web site that lists far more CVs that can be useful.
Most of the CVs are already programmed, Sam. However, some may just be programmed to "0" (Off). There are some that aren't programmed but are there for the "expandability" of the decoder. (Kinda like having a book shelf that you only utilize 1/2 of the space available.)
The reasons for reprogramming are many and greatly depend on what locomotive the decoder is installed in. A full 6-function decoder installed in a locomotive that had only a single headlight would work but would be somewhat overkill for that locomotive. However, on a more modern locomotive that comes with Mars lighting and ditch lighting, that same decoder could be programmed to utilize the flashing ability available on the decoder so that the locomotive operated like the prototype.
Sound functions are another example. Some decoders (e.g. Loksound Select) come with a variety of sounds available. While the manufacturer of the sound decoder may provide a decoder for a specific type of locomotive (e.g. a 567 prime mover for an EMD F3), each railroad may have used a particular type of bell or whistle for their own F3. By changing a certain CV, the user can then choose the appropriate bell or whistle for his prototype.
Another example would be which type of locomotive is the decoder installed in? The running ability of a yard switcher is VERY different than that of a passenger locomotive. Decoders can allow you to program a specific (pre-programmed or user-specific) speed table appropriate for your particular locomotive. Depending on the model, some decoders can allow you to fine-tune that switcher so that it just begins to crawl at speed step 001; very realistic and appropriate for a yard switcher.
Finally, yes - once you've programmed your locomotive's decoder how you want it to operate with your DCC system, it should work exactly the same on someone else's layout. The one difference might be whether or not the other DCC system has the same capabilities as the one you have. If you've programmed on your DCC system but the other guys system is 10+ years old, there are certain commands that his system may not recognize.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
OK guys, that explains a lot, thanks for that.
Brian, thanks for that link. Looks like I'll be doing a lot of reading on it.
Tom,
That's some good information, thanks. It's just that I buy all my loco's with factory installed sound decoders,and thought I didn't need to change the CV values, except changing the address only.
And the beauty of it is that you have that option, Sam. You can get into programming as little or as much as you want. I have an Atlas HH600/660 switcher (w/sound) that I haven't changed a single CV on and it crawls like a champ.
Everyone else has given you good answers about CV's, but here are a few more points.
All decoders have and use the same CV's for the basic functions. These have been set up from the NMRA standards. Other CV's such as those controlling sounds and other advanced functions will be different from one manufacturers decoders to another.
The brand of DCC system that you have will also determine how easy or hard programming a decoder will be. For one example, NCE has a simple way for setting CV 29. They ask you a series of questions as you are going through the programming steps. The answers that you give determines the value of CV 29. Other systems may make you calculate it and then program CV 29 with the value you came up with.
Since you have a computer, you can download and use JMRI's Decoder Pro. This requires your DCC system to have a computer interface connector and be an open system. (MRC is an example of a closed system where Decoder Pro will not work.) You will also need some type of interface device between your computer and your DCC system. The JMRI web pages will tell you what you need and walk you through the process. Now the question becomes, Why should I use Decoder Pro? Because it makes programming your locomotives a point and click process from your computer. You do need to know what decoder by make and model you have in all of your locomotives, but once set up, you won't look back.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
If you're looking for a book on DCC, I found The DCC Guide rather helpful as well as web info others have cited.
http://www.kalmbachstore.com/modeltrains-railroading-model-railroading-books-wiring-electronics-series.html
Paul
Modeling HO with a transition era UP bent
Sam, it's a good question, because I think a lot of people are intimidated when thinking about converting to DCC because they think decoders come from the factory "blank" and they'll have to spend hours entering CVs to get them to work. As noted, the only thing you really need to change is the ID of the decoder, usually to the number of the engine it's in. You can go back later and take advantage of some options that the decoder offers.
For a long time after converting, all I did with a new decoder was change the ID, put a value of 10 or 12 in CVs 3 and 4 to add a little momentum, and change CVs 49 and 50 from having the headlights being directional to having them bright in the direction of travel and the other headlight on but dim.