73
Bruce in the Peg
Because the NMRA standards left a lot of CVs unassigned and each decoder manufacturer is free to do whatever they want to use those for.
If you look at a list of the CVs used by any specific decoder, you'll notice gaps in the number sequence because the NMRA did not assign those CVs as "standard" but left it up to the manufacturers to use them if they want.
Digitrax, for example, uses CVs 1 through 8, then jumps to 13, then 17, 18, 19; then 29. From there they jump to 49. The intervening CVs were not assigned as standard by the NMRA; or if they are a standard, they're assigned to a function that Digitrax does not use.
isn't there a read only CV that contains the manufacturers name and model number ?
if there isn't ... why not ?
and if there is , why doesn't decoder pro just read it and figure out what decoder you have ?
ernie
It does. That's how the identification button works.
You will get multiple choices when the manufacturer uses the same code for multiple decoders. Most times, you can jusst pick one of the highlighted choices because all models found by Decoderpro will have the same feature set.
ereimer wrote: isn't there a read only CV that contains the manufacturers name and model number ?if there isn't ... why not ?and if there is , why doesn't decoder pro just read it and figure out what decoder you have ? ernie
Yes, there is. CV8 is the manufacturer ID number and CV7 is the decoder software version number.
Decoder Pro can query these two CVs and identify the decoder. My NCE PowerPro system, and possibly other brands, identifies the decoder manufacturer and version at the beginning of the programming sequence. The NMRA assigns each decoder manufacturer a unique number for CV8, and you can look those numbers up on the NMRA web site.
The latest version of the NMRA DCC manufacturer listing is at http://www.nmra.org/standards/DCC/standards_rps/Appendix%20A,%20RP%209.2.2%202008.06.11.pdf
cacole wrote: ereimer wrote: isn't there a read only CV that contains the manufacturers name and model number ?if there isn't ... why not ?and if there is , why doesn't decoder pro just read it and figure out what decoder you have ? ernie Yes, there is. CV8 is the manufacturer ID number and CV7 is the decoder software version number.
To expand on that a little:
While each manufcturer has a unique ID (stored in CV8), they may use the same firmware version (stored in CV7) for multiple decoders.
For example, a two-function and a six-function decoder might use the same firmware. The two-function model just lacks a few parts to drive the other functions. Or one may be a drop-in form factor while the other is a hard-wire style, but again, they both use the same firmware. And of course, DecoderPro cannot look inside the loco and see which physical decoder you have.
This has been discussed in great length on at least a couple occasions on the JMRI list. As a matter of fact, JMRI's behavior with regards to identifying decoders was recently changed to better accommodate this issue, and that change was also extensively discussed on the JMRI list. That's really the best place to get JMRI info, since the folks who actually write the code hang out there.
HTH,Steve