NCE momentum button

[ColinK]

Hi, I have a NCE procab and I know that pressing the momentum button should not be used for locos with sound decoders as pressing it can alter the values in some CV's. Indeed, I have two locos performing badly because of this.

 

So, is there a way of changing what the momentum button does eg reasigning it as a second direction button, to prevent momentum being pressed by mistake?

[WardRail]

Hi

 

You could remap it to be a brake button - how to remap buttons is explained pretty clearly in the manual

 

Another way round would be to lock the decoders, which stops decoders being written to or having values changed after they're locked. Again, locking decoders is explained in the manual and far easier than remapping the buttons. Basically you set the decoder the way you want and then lock it.

 

Best

Matthew

[Trainshed Terry]

Have you seen the manual for the power cab controller. You need a degree in computer programing     

 

Terry

[WardRail]

Hi Terry

 

As a pwercab user of course I have seen the manual. Its easy enough, but far easier to lock decoders and the instructions for locking decoders in the manual are easily understood, without any other manuals necessary IMHO

 

Best

Matthew

[Nigelcliffe]

Hi

 

You could remap it to be a brake button - how to remap buttons is explained pretty clearly in the manual

Are you *sure* this works ?    My reading of the manual is that it is possible to remap the "shifted" buttons, ie. those when the shift key is pressed.  My reading is that the only non-shifted button which can be re-mapped is "option".  

 

 

One solution is to construct a ring around the button from a thick material to make it more difficult to press accidentally. 

 

 

- Nigel

[WardRail]

Hi Nigel

 

Yes to both, momentum key (15 or shifted key value 111) can be remapped either on its default of 15 or its shifted value of 111 in the normal way using cab setup. Doug N gave instructions on how to do so in this forum some time ago

 

Locking the decoder also stops anything being written to it without it first being unlocked and is IMHO far easier to do. Powercabs won't unlock anything without user input

 

Best

Matthew

Edited December 5, 2014 by WardRail

[pauliebanger]

Matthew,

 

Thanks for the info on remapping PowerCab. I have warned may times about possible adverse effects the Momentum button may have on sound decoders. If this means I can get a useful function instead,that will be great!

 

However, I would question the reliance on decoder locking to stop the effect of the momentum button in all cases, as CV15 and 16 dcoder locking is not supported in all decoders.

 

ZIMO decoders have a CV144 lock which is only intended to prevent inadvertant Service Mode (programming track) Programming. This is to stop the programming of other locos at the same time which could be possible since Service Mode does not require the loco address prior to programming.

 

POM, on the other hand, is not prevented and it is this which the PowerCab will use to issue programming commands to change momentum of locos in operation.

 

If you think about it, if you 'lock' a decoder (by programming the relevant CV) how can you ever 'unlock' it if pregramming is prevented in both Service and POM programming modes?

 

For me, I think either a physical prevention as suggested by Nigel or avoiding the use of the button, or your suggestion of remapping the key are probably better strategies.

 

Kind regards,

 

Paul

 

Edited to be more accurate and representative.

 

Edited December 5, 2014 by pauliebanger

[pauliebanger]

Matthew,

 

I think Nigel is correct in his interpretation of the manual. The only button which can be remapped in its non-shifted state appears to be the Option Key. The instructions are the same for ProCab and PowerCab.

 

I can't see a way to remap the Momentum Button (NCE button 2). By default it is 111, Momentum.

 

The cab set-up allows only the SHIFTED NCE button 2 to be remapped, but as the default 'alternative' function for button 2 when shifted is 94, (brake) there is nothing required to map it to brake.

 

If you know of  a routine to remap the non-shifted Momentum Button, button 2, it would be very helpful if you could explain it, please, as the manual is 'quiet' on this matter.

 

The 15 you mentioned earlier is refering to NCE button 15, the SelectAccy button, whose 'default shifted function' is 111, momentum.

 

For other readers,

 

Just to clarify what 'Brake' means in this context. If you press a button which has the Brake function attached, the speed steps are instantly set to zero. There is no brake force applied, it just saves having to use either speed buttons or thumbwheel to reduce speed manually.

 

Kind regards,

 

Paul

[ColinK]

Hi, I am still trying to get my head round this. If I understand it correctly,

 

There is no known way of disabling the Momentum button or reallocating it to do someting else eg second direction toggle.

 

You can change what 'shift + Momentum' does, it is currently set as brake.

 

I had not appreciated that 'shift + Select Accessory' also acts as momentum. It would make sense for me to change this to something else. I have worked out how to do this from the manual.

 

In the absence of any electronic solution, I'll have to make up a raised ring round the momentum button as suggested

 

I had never heard of locking decoders, more info on which decoders can be locked, what locking does, how to lock and unlock would be appreciated.

[Worsdell forever]

If you inadvertently press the Momentum button nothing will happen unless you press a number, pressing prog/esc will cancel it.

[Nigelcliffe]

I had never heard of locking decoders, more info on which decoders can be locked, what locking does, how to lock and unlock would be appreciated.

Decoder Locking exists in the NMRA standard as a "recommended practise", so its optional. Not every manufacturer implements it, and not all implement it the same way. So, its a case of "read the manual for your decoder". In the case of LokSound V4's, they do implement locking and appear to use the NMRA method.

 

The NMRA method is to use CV's 15 and 16. A value of "0" in those CV's is the default and is "unlocked". Locking requires setting one to another value, and then changing the other to match (to unlock). If a decoder is locked, then it does not respond to any CV change requests. (I can't recall what happens in the standards with CV19, consisting, because a lock on every CV would mean that advanced consist instructions would also fail to work).

 

The original idea behind it was locomotives with multiple decoders; locking would allow one decoder to be changed without changing the other. The NMRA document even includes recommendations as to which values of lock are used for different classes of decoder. But it can also be used to stop accidental changes when a loco is in use.

 

 

(Note to any JMRI/DecoderPro users; decoder locking is deliberately absent from decoder definitions. This is because reading/writing a load of CVs from a decoder file and then hitting a "lock" value part way through could have all sorts of unexpected consequences. Used in isolation, through setting the lock CV values as individual changes, locking works fine. )

 

 

- Nigel

[ColinK]

Many thanks for the clear explaination Nigel. All but one of my decoders are Loksound (v3.5 and V4), so locking the decoder would solve my momentum problem.

 

Being able to unlock is important as I have the volume low for home use and higher for exhibhitions. So I can do that too.

 

The odd one out decoder is a Zimo.

 

Thanks again.

 

ColinK

[Nigelcliffe]

Many thanks for the clear explaination Nigel. All but one of my decoders are Loksound (v3.5 and V4), so locking the decoder would solve my momentum problem......

 

The odd one out decoder is a Zimo.

Of your list, only the ESU V4 decoders support locking. Its not in the manual for V3.5. Zimo only has lock against Service Mode (programming track) changes, not against Operations Mode (main line) changes. So, from your loco fleet, only a few could be protected with locking.

 

- Nigel

[Sunnysa]

Unless I am missing something, I have always been led to believe locking a decoder via CVs 15 & 16 only prevents it from being programmed.

 

 It does not prevent function keys being operable.

 

 In this case the momentum button will still function if decoder is locked.

 

 Cheers

 

  Ian

[Nigelcliffe]

Unless I am missing something, I have always been led to believe locking a decoder via CVs 15 & 16 only prevents it from being programmed.

 

 It does not prevent function keys being operable.

 

 In this case the momentum button will still function if decoder is locked.

 

Yes, you've missed something. The momentum button is a short-cut to "ops mode programing (using currently active locomotive) of CV 3 and CV 4, with values using pre-determined settings inside the PowerCab/ProCab handset".

 

The momentum button is not a "function key" in the sense of sending decoder function instructions to the track. 

[Sunnysa]

 Thanks for making things clearer.

 

I must admit, I know very little about NCE system apart from, as stated early in this thread, the momentum button can muck up the values in some CVs in certain sound decoders.

 

 Cheers

 

  Ian

[pauliebanger]

 Thanks for making things clearer.

 

I must admit, I know very little about NCE system apart from, as stated early in this thread, the momentum button can muck up the values in some CVs in certain sound decoders.

 

 Cheers

 

  Ian

 

Ian,

 

Full explanation here: http://www.rmweb.co.uk/community/index.php?/topic/89097-beware-nce-and-esu-momentum-idiosyncrasies/&do=findComment&comment=1549665

 

The NCE Momentum button mucks up the CV3 and 4 value in ALL decoders (capable of CVs 3 and 4 reprogramming). Look again at Nigel's explanation. It 'permanently' writes a value which it calculates based on certain know parameters. (Permanent in this case means until you change it again - it will not automatically 'revert').  

 

Non-sound decoders are equally affected, but the 'mischief is not so obvious as there is no sound to be impacted. However, if you use a non-sound ESU decoder speed-matched and in consist with any other decoder brand, the NCE momentum button will ruin all the careful speed and curve matching you have done. This is because ESU, for no stated reason I know of, has chosen to use a different multiplier than the standard NMRA. (this also applies to ESU LokSound too, but as well as destroying your speed matching, the sounds will not operate as designed either).

 

Kind regards,

 

Paul

Edited December 10, 2014 by pauliebanger

[Austrag]

A really solid fail-safe method is to open open the case and stick a small piece of cellotape or similar on the button contacts to stop the contacts making the circuit. The rubber buttons are carbonized and short across the printed grid. Conversely, if a button is erratic when pressed, a soft pencil like a 4B rubbed on the button will rejuvenate the contact for a while.

 

Take your choice. David

[ColinK]

Thanks for that David. I'm tempted to open it up and put some tape (insulation tape?) between the contacts, is it fairly straightforward or is there a risk of me wrecking the handset?

[Austrag]

Nothing to it. I fixed my unit this morning after reading the posts. The black part of the button is profiled as a dish to keep the two apart normally. The tape becomes a barrier between them.

 

Just unscrew the 9 screws, keep it with the buttons downwards, lift the board up over the pegs, which the screws fit into and it lifts out in one piece. Lay it aside carefully, ie don't drop it the window is fairly robust, then you can see the buttons, which are a one-piece item. I then cut the tape as a small square over the button. Re-assemble it carefully, do not overtighten the screws and that's it.

 

To put it back to normal, remove the tape and any residue using something like IPA track cleaner. David

 

[ColinK]

Many thanks for that David. I've just done both my ProCab's. Took about 30 minutes. Was very easy as you said - even for me. Hardest part was finding the insulation tape in my railway room. Such a simple, invisable, and reversable modification.

 

Now to find out what the CV's should be on my class 15 before the momentum button messed them up.

 

Thanks again,

 

ColinK

[cravensdmufan]

 

Nothing to it. I fixed my unit this morning after reading the posts. The black part of the button is profiled as a dish to keep the two apart normally. The tape becomes a barrier between them.

 

Just unscrew the 9 screws, keep it with the buttons downwards, lift the board up over the pegs, which the screws fit into and it lifts out in one piece. Lay it aside carefully, ie don't drop it the window is fairly robust, then you can see the buttons, which are a one-piece item. I then cut the tape as a small square over the button. Re-assemble it carefully, do not overtighten the screws and that's it.

 

To put it back to normal, remove the tape and any residue using something like IPA track cleaner. David

 

 

An excellent fix, very many thanks.  Even I completed it easily!

[GoGoffa]

Thanks David for the easy fix and Paul for raising the issue. With 18 locos with ESU Locksound decoders running on NCE DCC it was a great insight and a simple prevention. Only a few minutes to prevent much time identifying an obscure issue.

Thanks

[Dougjuk]

Worked a treat did my Powercab in 10 minutes even lightly cleaned and greased the wheel holder which was rubbing somewhat.

[shelton]

Does anyone know what the Brake button is supposed to do on a NCE PowerCab?  I press the button and it doesn't do anything.

 

Thanks

Shelton