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Author Topic: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'  (Read 2254 times)

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Offline jpendle

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Hi,

I've decided to post this as there seems to be an awful lot of confusion created by the advent of NeXT18 sockets in Dapol locos, and probably Farish as well.

So first, as manufacturers adopt NeXT18 they naturally want to exploit the extra features available, and that's a good thing. For example we can now have independent control of front and rear lights on our locos and MU's.

BUT this does mean that the days of 'easy' DCC are behind us, i.e, you can no longer plonk a decoder in a loco, set the address, press F0 and have all the lights work as they should, or more correctly, as they shouldn't. Because with a 6 pin decoder all the lights are on all the time even when the loco is hauling a train.

Now you plonk you chosen NeXT18 decoder in your loco and you find that F0 only controls the lights at one end, the other end 'doesn't work, works funny, etc'.

You have now reached the dreaded stage of 'reading the manual' and 'CV programming'  :D So what to do?

First some terminology (Boring  :sleep:)

Number 1 end:           The end of the loco that is at the front when your decoder thinks the loco is running forwards
Number 2 end:           The other end :D

Function key               The button on your controller that switches the Function on and off, this can be latching or non-latching.
Latching                     A function key that remains on after it is pressed, and has to be pressed again to be turned off (e.g F0)
Non-latching               A function key that is only on while it is being pressed (e.g F2 on American kit?)

Function Output          The physical output from a decoder sometimes referred to as an Auxiliary output
Auxiliary Output          See Function output

Binary                        A number system using ones and zeroes, to count from 0 to 10 in binary, 0,1,10,11,100,101,110,111,1000,1001,1010
Binary                        Technical definition, a Base2 number system, decimal is Base10.

Register                     The thing in the decoder that stores the CV values, there is at least one register per CV, each register is 8 bits long and thus is programmed in binary.
Bit                             Binary digit, a 1 or 0.

Binary to decimal conversion, or Google is your friend, if you need to convert b00001010 to decimal, you can get the answer on line, or do a degree in electronics  ;D
It's 10 by the way.

So back to the trains.

All the Dapol locos I have experience of, which have NeXT18 sockets, have been wired the same way, I am assuming that Farish will be similar, if not identical.

Function outputs 0f and 0r are wired to the head and tail lights at the number 1 end of the loco.
Function output F1 is wired to the headlights at the number 2 end, and Function output F2 is wired to the tail lights at the number 2 end.

Now, by default, function key 0 controls function outputs 0, function key 1 controls function output 1, etc, etc,

So a freshly chipped loco will work as follows.

F0 will control the DIRECTIONAL lights at the number 1 end of the loco.
F1 will control the headlights at the number 2 end
F2 will control the tail lights at the number 2 end

IF F2 on your system is non-latching, and you don't fancy reading the manual or doing any CV programming, then you can leave well enough alone and use F0,F1, & F2 to control the lights on your loco forever.

IF NOT then read on.

So how do you map Function keys to Function outputs so that you minimize the buttons that you press to get your lights working?

BTW this is not hard, soldering a kit is hard :D

The standard NMRA function mapping is supported on most decoders (but NOT ESU V4 or V5, Thanks Nigel) and works like this.

First a page from the Zimo manual, this freely downloadable so should be OK to post here.



This shows how the various function keys can be mapped to the different function outputs and which CV's control the mapping.

The left most column are the Function keys followed by the CV associated with that key, along the top are the function outputs.

The grey area shows which function outputs CAN be mapped to which function keys, e.g F1 can only map to outputs Front Light, Rear Light and FA 1 through 6,
F4 can only be mapped to outputs FA 2 through 9.

The Black dots show the default mapping, F1 to output 1, F2 to output 2, etc.

Mapping is achieved by setting the relevant CV to the required binary number, for example CV35 by default is set to binary "00000100" or decimal 4. Output 1 is set to '1' and all the other outputs are set to '0', remember this is a CV setting, the actual outputs are not being touched yet.

So how do we use this table to map our lights to a single function button?

Let's use F1 as an example. We know that by default CV35 is set to '4' so that F1 controls output 1, but we want it to control output 2 as well.

That means that we must look at the bits in the mapping table to work out which bits need to be turned on or off to acheive what we want.

Looking at the table the bits for CV35 should be set as follows "b00001100", or decimal 12. We are saying that when F1 is pressed we want outputs 1 and 2 to be controlled but not any other outputs.

Now, just to be on the safe side you should also unmap F2 from output 2, the default for CV36 is b00001000, decimal 8, i.e. F2 controls output 2, to turn this off CV36 should be set to b00000000.

So now if we press F1 BOTH sets of lights at the number 2 end will turn on

So we have fixed one problem but created another, F1 has no sense of direction and both head and tail lights will turn on when it is pressed.

This is also where you will need to read the manual of the decoder that you are using to determine which CV's to program to get the number 2 end lights to behave in a directional fashion. In the Zimo manual it is covered under Special Effects for Function outputs, which allows the programming of various US prototype lighting effects.

If, like me you are using Zimo decoders then you need to do the following.

CV127 controls the special effects for Function Output1, CV128 controls FO2.

FO1 controls the headlights, so these need to come on when the loco is running BACKWARDS, remember we are talking about the number 2 end of the loco.
FO2 controls the taillights and these need to come on when the loco is running FORWARDS.

So we set CV127 to b00000010 or 2, active in reverse direction only, and CV128 to b00000001, or 1, active in forwards direction only.

I hope that this helps and makes sense, please let me know how it could be improved.

Regards,

John P


« Last Edit: May 27, 2019, 06:15:46 PM by jpendle, Reason: Correction »
Check out my layout thread.

Contemporary NW (Wigan Wallgate and North Western)

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=39501.msg476247#msg476247

Online Bob G

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #1 on: May 27, 2019, 04:29:03 PM »
I think this is why I'm happy to have stayed DC

And, given the number of times the PCB fails on a Dapol loco, I kind of wonder why they are bothering at all.
Bob

Offline jpendle

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #2 on: May 27, 2019, 05:19:01 PM »
I think this is why I'm happy to have stayed DC

And, given the number of times the PCB fails on a Dapol loco, I kind of wonder why they are bothering at all.
Bob

Remember it's Farish as well, I just don't have a Farish NeXT18 loco yet to compare, but I guarantee there will be similar issues.

John P
Check out my layout thread.

Contemporary NW (Wigan Wallgate and North Western)

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=39501.msg476247#msg476247

Offline Nigel Cliffe

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #3 on: May 27, 2019, 06:02:20 PM »

There are about half a dozen ways of doing this arrangement in a Zimo decoder.  You've picked one of many. 
The NMRA mapping applies to most decoders, but not all.  Notable exception is ESU in their V4 and V5 decoders. 
The way direction dependency of function outputs, or function keys, is very much decoder maker specific, so the concept for Zimo hold true for many others, but how its implemented depends on decoder makers. 

Changing this sort of thing is really easy with DecoderPro and a computer hooked up to the DCC system to do the setup.


Latching behaviour of throttles on F2 depends on maker.  Some (usually US designs) are fixed as non-latching for the "horn" key. Some have two keys, one latching, one non-latching.   Some (mostly European designs) offer the user a choice of setting how F2 works, usually on a per-loco basis.  And smartphone throttles are generally configurable in software. 


( You've probably got "non-latching" wrong when describing Function 2 in your text  "If F2 is non-latching...."  - a non-latching key for the lights is a pain in the backside)



Offline jpendle

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #4 on: May 27, 2019, 06:12:10 PM »
Thanks Nigel.

I wasn't aware that ESU didn't follow the standard, but I was fairly certain, just not sure, that American systems typically have the horn assigned to a non-latching F2.

The main point of this thread is to warn people, like @mickster04 , on the Pacer thread, that things are different with NeXT18, so they don't end up trashing the wiring on their new loco because it doesn't work the same as with a 6 pin decoder.

Regards,

John P
« Last Edit: May 27, 2019, 08:31:37 PM by Newportnobby, Reason: Tag modified so it would work »
Check out my layout thread.

Contemporary NW (Wigan Wallgate and North Western)

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=39501.msg476247#msg476247

Offline Only Me

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #5 on: May 27, 2019, 08:24:03 PM »
Also on a Digitrax system you can edit the op sw to make F2 latching if you wish

Online Graham

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #6 on: May 28, 2019, 11:11:00 AM »
thanks for some great pointers, looks like a lot more reading of manuals at least in the short term. I must admit to struggling with my 68's to get the lighting to work how I want it. this helps no end.

cheers
Graham

Offline Nigel Cliffe

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #7 on: May 28, 2019, 12:04:31 PM »
Also on a Digitrax system you can edit the op sw to make F2 latching if you wish

On some Digitrax throttles yes the default F2 non-latching can be changed.  But not for all Digitrax throttles - depends what you own. 

Online njee20

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #8 on: May 28, 2019, 12:42:31 PM »
Does sound helpful, duly bookmarked (mentally!). My sole Next18 model is a 68, which seems to work as expected, but clearly they're going to become more prolific.

Why the random capitalisation though, isn't it just "Next18", rather than "NeXT"?

Offline jpendle

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #9 on: May 28, 2019, 02:26:04 PM »
I have seen it referred to before as NeXT, by Mr Nigel Cliffe, amongst others, so I think the N,X,T are the letters that matter.

John P
Check out my layout thread.

Contemporary NW (Wigan Wallgate and North Western)

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=39501.msg476247#msg476247

Offline ntpntpntp

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #10 on: May 28, 2019, 09:18:45 PM »
NeXT was a computer back in the late 1980s.   

The decoders seem to be generally referred to as Next18 or NEXT18.
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline Sparks

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #11 on: October 07, 2019, 08:30:40 PM »
Just had to search this out after getting my new Dapol Biffa 66 -   Thank you so much for going thru this John.....  I got there following your steps in the end (altho I glazed over in the middle there for a bit.... )     bottom line is that for things to work as they used to,  cv35=12,  cv36=0,   cv127=2, cv128=1   :doh: ??? -  and then all you need to remember is the on / off switch is now F1  (and not the button marked lights on a powercab as thats default F0)  :claphappy: :claphappy:    Simple huh ??   don't you just love this 'progress' were all making ??    Hope the box shifters are ready for all the returns calls hahaha.

Offline jpendle

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #12 on: October 07, 2019, 10:10:47 PM »
I'm glad it helped.

I noticed that the latest Dapol 66's AND 86's are now Next18 fitted, it seems like they have a rolling program to move away from 6 pin decoders.

Regards,

John P
Check out my layout thread.

Contemporary NW (Wigan Wallgate and North Western)

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=39501.msg476247#msg476247

Online njee20

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #13 on: October 07, 2019, 10:37:27 PM »
Does make sense, given their better handling of increased lighting functions and a move towards sound provision.

Offline Sparks

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Re: WARNING NeXT18 AHEAD!!!!! Or 'be careful what you wish for'
« Reply #14 on: October 08, 2019, 09:22:01 AM »


I noticed that the latest Dapol 66's AND 86's are now Next18 fitted, it seems like they have a rolling program to move away from 6 pin decoders.

Regards,

John P

I should have known it wasn't going to be simple when even the blanking plug has a light switch on it   :D :D

Cheers,
Dave.

 

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