28/128 Speed Steps and elink/Railmaster

[kjh58]

Hello !

I have an engine with an old DCC decoder from Arnold (81220) which only supports 14/27/28 speed steps. (CV29 bit 2=0/1)

I have set the decoder to 28 speed steps and can drive the engine with my Lenz DCC system but not with Railmaster/elink.

Am I right that RM/elink only supports 128 speed steps?  If so I can't use this decoder ?!

Perhaps someone can give me a short hint on this topic.

Thanks, Klaus from Germany

RM and elink 1.64, UK Layout 00

[96RAF]

Welcome Klaus

 

Reading the manual page 71 about changing CV29 there is a tick box for 28/128 speed steps so if you can read your decoder using RM then double click on the CV29 value it will show if your decoder is seen by RM as having 28 steps set. If not then tick this box and write the new value to CV29.

 

Rob

[kjh58]

Welcome Klaus

... CV29 there is a tick box for 28/128 speed steps .....write the new value to CV29.

Rob

Hello Rob !

Thanks for your answer, but that wasn't exactly my problem ;-)

Using 28 or 128 speed steps depends on 2 parameters: CV 29 bit 2 AND changing the number of speed steps transmitted to a locomotive by setting it per loco in the controller. If you have a look at the Elite manual page 45 "Changing the number of speed steps transmitted to a locomotive" you'll see what I mean.

While looking again through the pages of the eLink manual there doesn't seem to be the possibility to change this. That means the eLink can only control decoders set to 128 speed steps in CV29.

Is this so? Perhaps someone out there can give me the answer to this?!

Thanks, Klaus

 

[96RAF]

The only mention I can find in the RM manual is on page 25 last sentence of the scale speed paragraph where it talks about deselecting scale speed to enable global speed steps 0-127.

[Fishmanoz]

Rob, you can only have steps 0-127 if the decoder is set to 128.

 

Klaus, you cannot set anything in the eLink, it is just an interface between RM and your track.  Also, speed steps are set in the decoder, not the controller being RM. just follow the instructions above for setting 28 speed steps in CV29, that is all you need to do.

[96RAF]

The problem as I see it is setting 128 speed steps is a two event procedure, at the controller and at each decoder.

 

Elite and most other controllers have this facility and it appears RM has it in a odd way by selecting or not scale speed settings.

 

This brings me back to the problem I have seen (and still have at v1.64.1) in Pro in that in order to make the second large controller work properly, scale speed has to be deselected, thus according to the manual enabling 128 speed steps. Scale speed obviously sets something other than 128 speed steps In the program or maybe in eLink.

 

I have not checked yet to see what if anything happens to the Elite speed step setting if scale speed in RM is put to on or off.

[Fishmanoz]

I'm happy to be proven wrong on this but I believe the speed step setting in the Elite is simply a convenience to stop the throttle being overly sensitive if set to 128 when the decoder only has 28.  What I think happens in this case is that the Elite will have the loco running flat out when it sends its 28th speed step to the loco, and the remaining 100 steps of 128 do nothing.  If th Elite is set to 28 for that loco, then you have to wind the throttle much further to get to the 28th step.  Am I wrong?

 

With RM, there is no speed step setting as it doesn't need one, no matter what interface is attached to it, eLink or Elite (remember Elite is only an interface not a controller when you are controlling with RM).  What it does when you use scale speeds is to limit the maximum throttle setting to be the maximum scale speed of the loco, based on what you tell it is the actual loco maximum speed and how long it took to go around the standard loop flat out.  Clearly it must work out the speed step that makes this the case, but it doesn't have to change the number of steps available to it to do so.  It just doesn't use the steps above the one it finds to make the loco run at its maximum scale speed, whether that be one of 28 or 128.  Unticked scale speeds and the throttle will now allow all speeds steps, whether 28 or 128.

 

Forgetting the controller for now, we also know that the speed step bit in CV29 in the controller is used for more than speed steps.  It is used as part of making directional lighting work for a start, and my memory is hazy as to whether it affects other things too.  These other thing/s are quite separate to loco speed of course.

 

Does that make any sense and make things clearer?

[96RAF]

@fishy

Your logic seems correct (I was going to say logical) and clears the fog in my memory about certain things.

 

I had always thought that when you fiddled with a speed curve if you limited the top end value then the remaining curve was divided across whichever speed step range you had set. E.g. If you limit top end to 64/128 then each of these remaining steps would be half power of what it would have been if unrestricted, thus giving finer control of the restricted loco.

 

May be wrong and likely am but without getting the DCC book out and reading up on it all again I am open to correction.

[Fishmanoz]

I'm not sure either Rob, and also not sure if this is relevant to Klaus's problem.

 

Klaus, not sure why it doesn't work, I think it should. Try putting it on the programming track and read the CVs.  Does RM recognize the decoder type and that CV29 is set to 28 steps?