Programming with the Digitrax Zepher

[ebtbob]

Good Evening All,

       A question about programming with the Zepher.   In the book,  Mastering the Digitrax Zepher,  a Madison Mountain Publishing,  on page 22 is a box on the right hand side of the page with this statement.  "Lastly,  we highly recommend that you do not use decoders that only program in the Physical Register (PHYS) mode.   What decoders would these be.
       Second question from a customer today.   He is trying to program an engine on a program track in the PG mode,  and gets a dnd read out.  He assures me that there is a decoder in the engine.  Assuming that there is no wiring flaws,  faulty decoder,  or improper installation,  is it possible that this decoder is one that requires more power than the Zepher can produce?   I seem to remember discussions here,  before,  saying something about putting a resistor across the rails of the programming track.

[jward]

dnd means decoder not detected. there is an easy way to checque if the decoder is properly installed. since your customer is unable to get the zephyr to read the decoder or program it i am assuming it is still at factory default settings. as such, analog conversion should be enabled, and the locomotive should run on a standard dc power pack. if it doesn't, you'd better double checque the wiring.

not the ideal solution, but something i have done is to have a friend with another system (mrc, nce, etc) program the decoder. they don't seem to have the same problems reading decoders as digitrax does. also, interestingly, the zephyr does seem to be able to reset the factory defaults on a decoder it doesn't detect. i am not sure why, perhaps jim banner has the answer.

[Jim Banner]

Bob,
One type of decoder that programs only in the physical register mode is the original MRC decoders, both H0 and large scale.  These decoders do not support readback of CV's and the ones I have all too frequently lose their programming, particularly their addresses, when a short occurs anywhere on the layout.  I do not know if these problems are related to their physical register mode only programming or not.

Locomotives with Lenz decoders can give the Zephyr problems.  Reading back from decoder to command station is done by the decoder drawing pulses of current with the number of pulses equal to the value stored in the CV being interrogated.  Lenz decoders often draw less current than the minimum detection level of the Zephyr programming output.  The solution is to connect a 1000 ohm resistor across the rails.  The current drawn by the resistor is too small by itself to bother the Zephyr but combined with the current from a readback pulse can be detected.

On my home layout, I have two toggle switches controlling a siding which is used as a programming track.  One large, center off toggle switch connects the track either to the track output or the programming output of my command station.  A miniature toggle switch beside it connects a 1000 ohm resistor across the track, or disconnects it.  This works very well and I would recommend it over the suggestion of just laying a resistor across the rails.

I see Jeffery has been busy posting while I have been busy typing (scooped again!!) but he raises an interesting question.  I did not know that you can reset a decoder that you can not read.  But I did know that you can program a value into a CV without having the Zephyr read back the value of the CV.  Let me explain:

The "normal" way to changing a CV includes these 5 steps:
(1) press CV button (tells Zephyr to take next entry as CV number.)
(2) key in CV number.
(3) press CV-RD key (Zephyr reads back present value of CV and is then ready to take next entry as CV value.)
(4) key in CV value.
(5) press CV-WR key (Zephyr issues instruction to write CV value into CV.)

However, there is a quicker way of changing a CV value that does not require waiting for the readback.  It goes like this:
(1) press CV button (tells Zephyr to take next entry as CV number.)
(2) key in CV number.
(3) press CV button ( Zephyr knows it has the CV number so this tells it to take the next entry as a CV value.)
(4) key in CV value
(5) press CV-WR key (Zephyr issues instruction to write CV value into CV.)

This is documented on page 19 of the Zephyr manual.  What Jeffery has got me wondering is whether you can use this as a work around for Lenz decoders i.e. program them without reading back.  We know we can do that in OPs mode for all CV's except address but maybe these instructions will work for all CV's.  Time to find out.


Jim  

[ebtbob]

Thanks guys.   I will check this thread again,  in the morning,  before I leave for the store.   Hopefully,  between you people on the forum and me,  we can help this person with his problem.

[Jim Banner]

My Guru advises me that skipping the CV-RD (CV read) step works only if the error is a dnr error and does NOT work for a dnd error.  So back to the 1000 ohm resistor.

He also directed me to this article:
http://www.digitrax.com/kb/index.php?a=1102

Jim

[rich1998]

in addition to this forum, the below group focuses on digitrax products and very active.
http://groups.yahoo.com/group/Digitrax/
lex

[ebtbob]

Guys,

      Thanks for the help.   Unexpectedly,  the customer showed up at the store instead of calling and we were able to program the engine on a Chief system.   I had a book about the Zepher and gave that to him plus a print out of the first two responses,  from jward and Jim as that was all there was before I left for the store.
      Thanks again.   BTW......Tim Anders,  who shows up here occassionaly,
stopped by the store to see me today and said that he found the Digitrax yahoo group that Lexon mentioned was VERY interesting.   Thanks lexon.