Changing CV values using Hornby Elite for Digitrax SDN136PS sound decoder

[Leighton Cook]

1. Can you change the "CV" values on a Digitrax SDN 136PS sound decoder using the Hornby Elite with firmware 4.3 ?.

2. I am able to change the locomotive address only.

3. Have tried many times on a programming track and the Elite displays all the signs of     acceptance but to no avail.

4. If I have to I will update the Elite to firmware 4.4

Any advice would be greatly appreciated.

[96RAF]

You mean v1.44.

 

The Elite is NMRA warranted and will work correctly with any DCC product that is NMRA compliant, not necessarily warranted.

 

There is the possibility you may have to use Register mode to change your CVs rather than Direct mode.

 

Certain CVs can be changed in Operations mode on the main track where full track potential is available. It has been noted that some sound decoders need more oomph than is available on the limited current programming track. Note that you cannot normally read back CV values on the main.

[Chrissaf]

Just for correctness of information for other readers. The Elite firmware is 1.43 or 1.44 not 4.3 & 4.4

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Digitrax is an American sound decoder brand. It is known that some of these American designed sound decoders can be difficult to CV configure using European controllers due to the European controllers having much lower power output limits on their 'Prog' track outputs.

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Have a read of this PowerPax online review article that mentions Digitrax sound decoders.

https://www.model-railroad-infoguy.com/programming-booster.html

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The issue discussed in the above article is that some US based sound decoders have a high in-rush current and suck all the power that is available from the lower power output of European designed controllers (such as the Elite).

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PS - I use a PowerPax with my Elite and it solved all my previous sound decoder programming issues. But I was using Loksound decoders and not any of the American brands. I wrote a review post about my PowerPax experience and it can be read here:

https://www.hornby.com/uk-en/forum/how-to-get-robustly-reliable-cv-readingwriting/?p=1

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Now I am not suggesting that you purchase and install a PowerPax, I am just offering this information as a theory as to why you might be experiencing some configuration difficulties with your Digitrax sound decoders and Elite. There may be other reasons, like dirt & grime on the wheels or programming track. User error etc. After-all, we have to assume that your are using the correct configuration process as documented in the Elite manual.

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But if we assume that the issue is fundamentally a low 'programming power' issue. Then one simple way that this might be resolved is to use the Digitrax 'Operations Mode' programming which is supported by the Elite controller. Hornby Elite documentation refers to this as 'Operate' mode. Operate mode means that full track power is applied to the decoder during the act of trying to change a CV. Thus if the issue is one of 'high inrush' current, then the full track power being present should alleviate that.

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Comment for eLink users. RM and eLink does not support 'Operate' mode. In which case, installing a PowerPax (or something similar) may be the only solution option.

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Below is an extract from the Digitrax SDN136PS manual, that states that the decoder supports 'Operations' mode. Service Mode (Direct option) by the way is the normal Elite programming mode using the Elite 'Prog' output, which Hornby document as being termed 'Direct Mode'.

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/media/tinymce_upload/8f272bf5da6b78cf3ab9f5813afaac46.jpg

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Now in order to use 'Operations' mode. Two things must be done:

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• Firstly, (to be safe) disconnect the main layout from the 'Track A&B' output of the Elite. In it's place, terminate your piece of programming track [currently connected to your 'Prog A&B' output] to the 'Track A&B' output instead.
• Secondly, put your Elite into 'Operate Mode' see page 41 of the Elite manual.

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Now follow the configuring CVs in 'Operate Mode' instructions, Elite manual pages 40 to 43 to try and change the CVs you want to change.

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Note that you won't be able to read back CV values in 'Operate Mode' unless RailCom support is turned on in CV29 of the decoder (if the decoder supports it). So since the CV29 value is probably currently default, and your issue is CV writing. Then reading back CVs in 'Operate Mode' is probably currently disabled.

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Reinstate all the normal Elite settings and track connections so that you can test to see if the changed CVs have been accepted.

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If this fails, you might try the Register and Paged Elite programming modes with the loco back on the 'Prog A&B' track connection. But that might invoke the power issue again if that is what is the primary cause of the problem.

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EDIT: Rob posted whilst I was busy writing mine. His suggestion basically mirrors mine, but mine has more supporting detail in it.

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Postscript Edit:

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I have also observed that due to the low power of the Hornby 'Prog A&B' output, the sprung loaded contact terminals of the Elite and eLink controllers can become tarnished (oxidised) over time. This further affects the reliability of CV reading & writing. To overcome this, I find that rolling up a piece of 'wet n dry' into a stiff tube then flattening it so that it about 5mm wide, then working it back and forth under the spring pressure of the push up terminals. Can make significant improvements in CV reliability, particularly if coupled with stripping back the insulation of the programming track connection wires to reveal fresh clean shiny copper.

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[Leighton Cook]

1. Thanks for all your help and sorry about my mistake as to the Elite firmware which should read : "The Elite firmware is 1.43 or 1.44 not 4.3 & 4.4"  Mind ahead of the typing syndrome

2..Do I have to "Rail Com Enable" via CV29 before I try to change the CVs - if it works?

3. I have read the Elite Manual many times &. I have tried DIRECT, REGISTER ,PAGED and OPERATE progammings but with no success.

4. I will throughly clean all the main and Programming track plus the Elite connections and then do a multimeter test for voltage/amp flow on all of these items and retry.

5.N.B.:- Thanks to RAF96 & Chrissaf`s excellent previous researched comments QUOTE:"some US based sound decoders have a high in-rush current and suck all the power that is available from the lower power output of European designed controllers (such as the Elite).

6. I will advise the outcome within a couple days.

[Chrissaf]

Do I have to "Rail Com Enable" via CV29 before I try to change the CVs?

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No.

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I will thoroughly clean all the main and Programming track plus the Elite connections and then do a multimeter test for voltage/amp flow on all of these items and retry.

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You will not get any voltage / current readings on the 'Prog A&B' output. That is completely normal. Any voltage that is applied on that output is a very brief transient voltage for which the measuring latency of modern multimeters is too slow to register. You can only capture these brief pulses using an oscilloscope. The voltage is only applied to the output long enough to transmit the programming Data Packet and that only lasts so many milliseconds. This is the crux of the issue with these American decoders as the pulse is too short to charge up the components used on their sound decoders. Not helped by the 'Prog A&B' output being 'current limited' to a very low level as well.

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If you did have access to an oscilloscope, then the scope trace would look something similar to this:

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/media/tinymce_upload/ef5a15998b5664c1e5a8401ea22e7ecc.jpg

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This example image (taken from the NMRA S9.1 standard) is based on a control packet being sent to the main 'Track A&B' output. A scope trace of the 'Prog' output would look similar, but wouldn't contain the 'Address Byte' as it is an 'all address' broadcast packet.

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I doubt very much that you have access to an oscilloscope, but just in case you do. Be very cautious as connecting the ground [earthed] connection of the scope probe if not floating can potentially damage the controller output semiconductor components.

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Note: On the main 'Track A&B' output expect to measure a voltage between 13.5 and 15.5 volts using a multimeter on the AC voltage scale. I have quoted a range of acceptable measurement voltages because the DCC track signal is not sinusoidal and you need special 'True RMS' DCC specific voltmeters to obtain an accurate reading.

[Leighton Cook]

Thanks Chrissaf - or do you prefer Chris?

[Chrissaf]

I don't have any axe to grind either way.....but Chris is a more friendly salutation.

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PS - I have finished editing my reply after your last visit....so review the new additions to it.

[Leighton Cook]

 Thanks for all your help Chris.

1. Used "Operate" Mode on main track to ensure maximum electrical current was available for the locomotive pick-ups and all is well.

2. Digitrax Decoder is NMRA Compliant as you said so the problem was not to use the "Programming" track.

Thanks one and all.

[Chrissaf]

3. I have read the Elite Manual many times &. I have tried DIRECT, REGISTER ,PAGED and OPERATE progammings but with no success.

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Since you said in an earlier reply that you used the 'Operate' mode without success. I take it that on that occasion you didn't connect your loco to the Elite main 'Track A&B' output. As you have found out, 'Operate Mode' does not use the programming track output.

[Leighton Cook]

 I was given CV & Values for F1 to transfer a part functions to F3 by Digitrax Help Desk.

F1 had a "Bell" continuous ringing sound associated with the free GREEN WIRE used in conjunction with the free BLUE WIRE for additional train functions which I used for the "constantly on"  loco Head & Tail light lighting as normal with any NMRA compliant decoder.

 I found out later from Digitrax Help Desk that they were not sure  which CV & Values for F1 would work to transfer the locomotive Lights to F3 which only had one "puff" sound when activated and would be less annoying when operating the loco lights than have the lights on accompanied by the continuous "Bell" ringing sound.

The CV`s & Values for F1 & F3 were an experiment and that Digitrax Help Desk were not sure what would be accepted or not by the Digitrax Decoder.

It was just an accident that the correct CV & Values last given to me by the Digitrax Help Desk worked when I was using the main track for programming.

The programming would have worked on the "programming track" as well because I was finally given the correct CV & Values information.

So the problem was not with the programming system but with unacceptable CV & Values given to me by Digitrax.

I was not aware that Digitrax Help Desk were only experementing with the values of the CV`s and that the programming may not work until they found the correct combination after each of my 'failed" programming attempts with their suggestions.

Why the GREEN WIRE was connected to the F1 decoder function at the Digitrax Factory is still a mystery to me.

Thanks once again for all your support and help.

 

[Chrissaf]

Thanks for the clarification.....