Decoder Problems

[tmiller]

Hay guys. I have a Bachmann GP9 with DCC on board. I was trying to speed match the loco. Somehow I managed to mess something up in the decoder. I have tried programming on the program track, setting the address to #3, setting CV 125 to 1, to restore the factory settings. Nothing. What I have now is a loco that the back light will work, no front headlight, and no movement.

Talk me through the factory reset if I have it wrong. Is there something I am missing? In the process I hit CV 30 and programmed a "0" data. But I can't find any setting for this CV. I have done some programming, but am in no way an expert.

Any help would be appreciated.

Ted

[tmiller]

Making progress. I reset CV8 to "8". Now it is working with address #3. But when I try to input a 4 digit address, it will not respond. Change it back to #3 and it works. I originally had a 4 digit address in, so I know it will take it.

Any advise from the experts?

Many thanks in advance.

Ted

[jward]

you didnt mention what dcc system you are using to program it

[tmiller]

Using a MRC Prodigy Express with an additional Prodigy Advanced cab.

[jward]

some systems, the digitrax zephyr i use is one, don't like the bachmann decoders. when programming a bachmann locomotive, i have to put a 11k ohm resistor across the program track to get my system to recognise and program the decoder.

my dad has a prodigy system. i had 2 bachmann gp40s which he addressed on his system which were completely dead on mine. i was about to take the decoders out and replace them when jim banner sent me the following:

The preferred consisting method with the Prodigy Advance is Advanced consisting.  This is done by programming the consist address into CV19 of each of the locomotives.

The easiest way of removing locomotives from advanced consisting with the Zephyr is to program a zero into CV19.  You can do this on the programming track using direct mode programming but only if you connect a 1000 ohm resistor across the track.

Almost as easy is to program a zero into CV19 with the locomotive on the main and with all other locomotives off the track.  Because you do not know the address of the locomotive, use address 00 with OPS mode programming.  This will send the command to all addresses, thus the above caveat.   

Once you are out of advanced consisting, the locomotives should run on their former addresses.  If those are unknown, reset the decoders to their factory defaults by programming an 8 into CV8.  Now they should run on address 03.

You might want to try this out before changing decoders, both for you own satisfaction and to check that there is nothing mechanically wrong with the locomotives.

Non operation on dc is a result of programming the locomotives with Prodigy.  Its default is to turn dc operation off.  Zephyr's default is to leave dc operation as it was and let you decide if you want to change it.

thanks again to jim banner for the above tips. they worked for me and maybe they'll work for you too,

[tmiller]

Jeff,

When I first got the unit, I think all I did was enter the 4 digit address when on the programming track. It took just fine. Now, since I had to reset to the factory default, when I enter the 4 digit address, the rear light turns on, regardless which direction I have it set to, and there is no movement of the engine. Then if I go back and reset it to address #3, it works just fine.

Now to compound my problem, if I do a consist using the #3 address, it apparently does not like it. Neither engine will run. But when I clear the consist, both engines will run on their own. So #3 is screwing up the consist, which really makes no sense

This is really goofy because up until today when I started fooling around with the programming, I had both engines running in a consist. So somehow, some way, it does not like the #3 address. That is the only thing that has changed, period.

Now I read where I can manually enter data into CV 17 and 18, that will correspond with my road #, but I am positive I did not do that originally. So what has changed?

So I think once I can get it back to recognizing the 4 digit address, everything will come together. Does that make sense? Oh, by the way I am running DCC, not DC.

Ted

[Jim Banner]

When you program a 4 digit address with your Prodigy, does it automatically program CV29 for you or do you have to do that yourself as a separate step?  If you program CV17 and CV18 individually, you will definitely have to program CV29 too.  Don't forget that the numbers you have to program into CV17 and CV18 are NOT simply the first two digits and the last two digits of the address.  Here is what the NMRA has to say about it:

Configuration Variables 17,18:       Extended Address 

The Extended Address is the locomotives address when the decoder is set up for extended addressing (indicated by a value of "1" in bit location 5 of CV#29).  CV#17 contains the most significant bits of the two byte address and must have a value between 11000000 and 11100111, inclusive, in order for this two byte address to be valid. CV 18 contains the least significant bits of the address and may contain any value.

How I usually calculate CV17 and CV18 with a scientific calculator, such as the one built into Windows, is as follows:
(1) set the calculator to decimal notation and enter the four digit locomotive number.
(2) switch to hexadecimal notation and add C000.
(3) write down the first two hex digits and the last two hex digits.
(4) clear the calculator and enter just the first two hex digits.
(5) switch to decimal notation.  This is the value you enter into CV17.
(6) switch to hexadecimal notation, clear the calculator, and enter just the last two hex digits that you wrote down.
(7) switch to decimal notation.  This is the value you enter into CV18.

for example, locomotive number 2468:
(1) set for decimal and enter 2468
(2) switch to hex and add C000 calculator reads C9A4
(3) write down C9 and A4
(4) clear, enter C9
(5) switch to decimal, read 201 and program this 201 into CV17
(6) switch to hex, clear, and enter A4
(7) switch to decimal, read 164 and program this 164 into CV18

Now program CV29 for 4 digit addressing (extended addressing).
(1) read back the value of CV29
(2) add 32 to that value
(3) program the total into CV29

Where did that value of 32 come from?  From a table of bit values (second row. below) corresponding to the bit numbers in a standard 8 bit byte:

bit number =     7     6     5     4     3     2     1     0
bit value =      128   64   32   16     8     4     2     1

The procedure for setting CV29 for 4 digit addressing puts a 1 in bit number 5 by increasing the value of the byte that is CV29 by 32.

If you like, you could read back the present value in CV29 and see if it is 32 or more.  If it is less, then the decoder is NOT set for 4 digit addressing.

Remember: don't shoot the  messenger.  It wasn't me who designed this system.

Jim

[Jim Banner]

I suspect Hunt's method is easier if you do not like to work in hexadecimal.  Both methods add  49152 to the complete 4 digit address or 192 to the first two digits of the address.  As a Digitrax user, I normally let the throttle look after the calculations for me but once in a long time I use the method in reverse to figure out what long address is programmed into a particular locomotive.  On an even rarer occasions, I have used this method to program a long address between 0001 and 0127 into a decoder, a job not normally allowed by Digitrax throttles.

Jim

[tmiller]

Thanks Hunt for that information. Very helpful, especially the calculator.

Now for the easy question, for which I need some guidance. Do I simply go into programming with the loco on the programming track, and without changing to the 4 digit address ( i.e. leave it set at address #3), start changing CV17, 18 and 29? Then when I am done it will come up and work under the 4 digit address?

I want to make sure the proper steps.

Thanks for all your help.

Ted

[tmiller]

Hey guys, I finally got the 4 digit address to work. Using the MRCC Computer interface did it. Although I should be able to program from a cab, apparently in this case it would not take. Once I got CV 29 set to 35, all is well on the railroad.

I also discovered how to read all the CV's for all the locos using the computer interface, and now have them in .txt files, for reference and comparison when I go to do my speed matching. It is invaluable information to have on hand.

I am so appreciative of all the advice and experience that you guys have to offer. I can't thank you enough. Thanks a million.

See you down the tracks!

Ted

[tmiller]

Yes I have had the MRCC computer interface all along. Sorry if I misled anyone.

Interesting you mention the value of CV29 as 34. I see where most of my locos are programmed to 34. And the loco that I had problems with, I set to 35. So, in the case of 34, if I understand you, long hood should be forward, and short hood would be reverse?

I think that all my locos are running short hood forward, and long hood reverse. Hmmm.... If I have time later this evening I will test them individually to see how they operate, and compare that with the CV value. And it will help now that I have a list of CV values to reference each loco.

Be back with you guys later. Another day of learning on the railroad.

Ted