Choosing DCC Addresses for Multiple-Units

[Riddles]

On 25/08/2021 at 16:03, Pete the Elaner said:

 

I did wonder what to number my APT-E. I don't know how TOPS coped with it!

My APT-E decoder is 2783 which are the keys you would use on an old mobile to text APTE.

Similarly, my KR Models English Electric Gas Turbine Prototype "GT3" is 483.

I don't need to remember though, as they are on my Z21 app. with thumbnail pictures.

Edited August 29, 2021 by Riddles
Punctuation

[Junctionmad]

…

Edited August 30, 2021 by Junctionmad

[jamespetts]

I normally use the unit's TOPS number as shown on the front of the unit, minus the letter. So, for example, this unit:

 

Graham Farish class 101 by James Petts, on Flickr

 

would be 840;

 

this unit:

 

Dapol class 121 by James Petts, on Flickr

 

124;

 

this unit:

 

Dapol class 121 by James Petts, on Flickr

 

131;

 

this unit:

 

Express train meets local by James Petts, on Flickr

 

204;

 

this unit:

 

Graham Farish class 101 by James Petts, on Flickr

 

207; and

 

this unit

 

Dapol Class 122 by James Petts, on Flickr

 

1. (As seen here, it did wear just "01" as a number at one point).

 

For units that carry the full three digit TOPS class as part of their number, such as the class 150 (I seem not to have any pictures of my class 150), 1 + the three digit number, e.g., 1001.

 

My general numbering scheme where the displayed number includes the class number is to take the first digit of the class plus the three unique digits of the locomotive/unit.

Edited August 30, 2021 by jamespetts

[96701]

On 29/08/2021 at 15:33, Riddles said:

My APT-E decoder is 2783 which are the keys you would use on an old mobile to text APTE.

Similarly, my KR Models English Electric Gas Turbine Prototype "GT3" is 483.

I don't need to remember though, as they are on my Z21 app. with thumbnail pictures.

My KR Models GT3 is 7203. G being the 7th letter in the alphabet and T being the 20th.

[melmerby]

What about 21C1, that could be 2131 but 21C100?

 

The problem with all these nomeclature systems is that the decoders still only do 1-9999 (or 10254 etc.)

So whatever your graphic/alphanumeric DCC system uses you still need a 4 digit DCC address that is meaningful for the decoder

 

Maybe it's time for an extra couple of bits to be allocated to the DCC packet for numbering?

That would give, if all 16 bits fully utilized  a decimal of 1-999999 (plus!), the current system uses 14 bits and not all are set.

The extra bits could be in an unused CV and maybe selected in CV29 (bit 7or 8), to be ignored by legacy systems but used on capable systems.

Edited October 13, 2021 by melmerby

[WIMorrison]

Keith,

 

I am not sure that all command stations support as far as 9999, I think that Digitrax only supports 9983, and I am sure that there are others that stop short of 9999 - and not all support short addresses up to 127, with some stopping at 99

[Ron Ron Ron]

1 hour ago, melmerby said:

....Maybe it's time for an extra couple of bits to be allocated to the DCC packet for numbering? ......

 

That's not going to happen in DCC.

It breaks the standards and you've effectively created a new protocol.

 

The Ring Engineering RailPro system , which is not DCC (...it's more advanced than that.....), uses decoders that have their own unique, permanent address, out of the factory. 

The user assigns an alphanumeric alias (loco naming) which is stored in the decoder itself and will be read on any RailPro system.

That alias can also be changed at any time.

The actual decoder address is of no value to the user, as it lives in the background, out of sight.

Any future standard DCC replacement would almost certainly have a similar approach.

 

In the meantime, if you want more than 4-digits on DCC, then it's loco naming or resorting to abbreviated loco numbers.

 

 

.

Edited October 13, 2021 by Ron Ron Ron

[melmerby]

1 hour ago, Ron Ron Ron said:

 

That's not going to happen in DCC.

It breaks the standards and you've effectively created a new protocol.

 

.

Surely Railcom was added about 10 years after the original DCC standards were agreed?

Lenz with Zimo & others developed it and offered it to the NMRA DCC standards group

 

So why not use some of the unused CVs and bits? (several are marked by NMRA as reserved for future use.)

1 hour ago, Ron Ron Ron said:

In the meantime, if you want more than 4-digits on DCC, then it's loco naming or resorting to abbreviated loco numbers.

Which the Z21 & Maus does but it doesn't address the decoder limit.

Edited October 13, 2021 by melmerby

[NIK]

2 minutes ago, melmerby said:

Surely Railcom was added about 10 years after the original DCC standards were agreed?

Lenz with Zimo & others developed it and offered it to the NMRA DCC standards group

 

So why not use some of the unused CVs and bits? (several are marked by NMRA as reserved for future use.)

Hi,

 

As to Railcom it seems to be backward compatible with the NMRA specification.

It appears not to put any signal onto the DCC bus that can be misinterpreted by a DCC compliant decoder. It also doesn't appear to slow down the frequency of speed commands which is vital to a model railway control system.

 

Regards

 

Nick

[Ron Ron Ron]

1 hour ago, melmerby said:

Surely Railcom was added about 10 years after the original DCC standards were agreed?

Lenz with Zimo & others developed it and offered it to the NMRA DCC standards group

 

So why not use some of the unused CVs and bits? (several are marked by NMRA as reserved for future use.)

 

 

RailCom was developed by Lenz, who subsequently licenced it to the NMRA.

Lenz joined with Zimo, TAMS & Kuehn to help develop the protocol that enabled RailCom to eventually become the NMRA standard for Bi-Directional communications.

ESU developed RailCom Plus as an extension and enhancement to RailCom, working with Lenz (the licence holder) to get it to market.

RailCom Plus is not part of the NMRA standards.

 

I don't know if it's technically possible to use any of the reserved, or unused higher function CV's for that purpose.

I was under the impression it wasn't.

 

As the NMRA is dictated largely (and understandably) by the needs of the US modelling market and the domestic manufacturers who serve it, I think it unlikely there'll be a call for such extended addressing.

They don't really need it and the domestic manufacturers, apart from TCS, are heavily invested in their dated DCC systems.

Crikey, it's taken nearly 15 years for just one US DCC manufacturer to wake up to the existence of RailCom and the others are showing no interest.

I would guess there's a fat chance of an extended address range, which none of their systems could cope with.

 

.

 

 

.

[Dungrange]

4 hours ago, Ron Ron Ron said:

In the meantime, if you want more than 4-digits on DCC, then it's loco naming or resorting to abbreviated loco numbers..

 

2 hours ago, melmerby said:

Which the Z21 & Maus does but it doesn't address the decoder limit.

 

I don't understand the problem with the decoder address limit - I don't know anyone with a layout large enough to accommodate 9,999 locomotives.

 

To return to the original question, I don't think there is a way of reducing a six digit number that will work for everyone.  At the moment I only have two decoders, so I've not given too much though to a numbering system.  For locomotives, I intend to use the class number for the first two digits and the last two digits of the locomotive number for the second two digits.  That is, 37405 would be 3705.

 

I only have four types of diesel multiple units: classes 156, 158, 170 and 221.  Effectively, I think I have two choices:

1. use the three digit class number and then allocate a number to represent each unit, probably based on the last digit - eg 170402 would become 1702
2. omit the leading class digit and then use the last two digits of the number as I plan to do with locomotives - eg 170402 would become 7002

The benefit of the first approach is I can pretty well guarantee no conflicts with other locomotive addresses, as I have no locomotives of classes 15, 17 or 22 and probably never will.  The downside is that I can only have a maximum of ten multiple units of the same class. I already own about seven or eight class 158 units.

 

The benefit of the second approach is that I could, in theory, have up to 100 multiple units of the same class, but the downside is that there is greater scope for clashes with locomotive addresses.  I don't currently possess any locomotives of classes 56, 58 or 70, but I am more likely to acquire a model of these classes than I would a class 15, 17 or 22.  I'm unlikely to ever purchase a class 21, but I may well acquire both a class 20 and a class 220, so again there would be scope for conflict between locomotive and multiple unit addresses.

 

Obviously for others, the potential conflicts will differ depending on the stock that they own or plan to purchase, so what suits one person wouldn't suit another.

 

For unique locomotives, like GT3, I'd probably just pick a short address such as 3 since I'd find that easier to remember than trying to make a four digit address.