Thank you for your comment Jean

I have 4 RM-88-M-O per bus.

I will inform them (forget)

I connected a red wire to both LDT decoders and the contacts work.

It's weird because in theory only one connection to the B terminal of the cs3 for the whole bus.

The LDTLifftinski site is quite well documented and it's quite laborious to find what you need.

I think I'll do better: I'll write to the technical support and ask them if all the decoders should be connected to the B or if one per bus is correct. And I'll report their explanation here.

I have another solution: sell the LDTs here and buy marklin. I will see

Good sunday

Thewolf

It was built like your diagram

Module 1 of bus 1 was working, not module 2 or modules 1 and 2 of bus 2

I wrote to LDT lifftinski

This is what I wrote :

'' Hi Mister,

I have a small problem with the S88 feedbacks.

I have a cs3 60226 marklin, a linkS88 60883 marklin and 8 LDT RM-88-N-Opto.

I will have 2 buses with 4 LDT decoders.

I've done some testing. I have mounted bus 1 with temporarily 2 decoders. I connected a red wire from the LDT decoder to the ref terminal at the B terminal of the cs3. The contacts of module 1 work, not those of module 2. I have connected a red wire to the second module in addition to the first and the contacts of both modules work. It seemed to me that one connection to an LDT decoder was enough for all the decoders on the bus.

Can you tell me the best way to do this?

Thanks in advance.''

His answer :

'' Sehr geehrter Herr Hamiot,

ich kann nicht sagen, ob Sie 2 oder 3Leiter fahren und habe Ihnen deshalb alle Anschlussbeispiele angehangen.
https://www.ldt-infocent...p?id=en:ab_rm_88_n_o_3lg

https://www.ldt-infocent...p?id=en:ab_rm_88_n_o_2lg
Sollten sich weitere Fragen ergeben, melden Sie sich gern.
Mit freundlichen Grüßen

Harry Conrad
Modellbahn-Support
033439 867-32

Mail: littfinski@buehler-electronic.de
WWW : www.buehler-electronic.de

Bühler electronic GmbH, Ulmenstraße 43, 15370 Fredersdorf
Handelsregister: HRB 1351 Frankfurt (Oder)
Geschäftsführer: Philipp Tietze, Sebastian Wolff.''

1-I can't do anything with his answer
2-It doesn't answer my main question, which is whether to connect all the modules to the B of the cs3

I write to them again:

'' Thank you for the answer

Unfortunately you did not answer my question.

I thought it was a simple one.

In a bus made up of 4 of your RM-88-N-0 decoders, should all the decoders be connected to the B terminal of the Marklin cs3 (red wire) or only the first one?

Thank you ''

I am waiting for the answer.

I have put all the LDT modules in my possession up for sale.

If the sale is successful, I will buy 60881s from my dealer and friend Mike.

At least with Mike I am sure of the best support there is.

By the way, I don't understand why I bought LDTs. It's really beyond me.

If the sale fails, I'll have to go through and find out what's wrong with the modules 2 on bus 1 and bus 2 that are mounted correctly

Thewolf

Sorry, I linked to the wrong sample connection, this is the basic setup:

https://www.ldt-infocent...ssbeispiele/page_668.pdf

My previous link, with the diodes, represents the basic setup plus the ”diode-trick”. This enables some grounding to both outer rails in a contact track section, i.e. not only one of the outer rails which could be the case with the basic setup for some engines. Secure grounding is more important on track sections where trains might be commanded to stop, which they sometimes will do on contact track sections. The diode-trick could be applied for any S88 module, i.e. not only for LDT modules. I’ve applied the diode-trick on all 80 contact track sections I have. Some do this, some don’t.


I would suggest that you plan for a thicker red wire for each booster you are planning for, and one thicker brown wire for common grounding, and let these wires follow your tracks as a kind of ”bus” under your layout. I use 1.5 mm2 cables for this. On strategic locations, e.g. each 4-5 meter, you then add simple but longer distribution plates for connecting feeders and grounding to your tracks, switch decoders and S88 modules.

There are cheaper alternatives to the Märklin 72090, with more outputs. I buy ”sugar cubes” as on the pic below, and run a thinner uninsulated copper wire in zig-zag through it, to derive the distribution feature. (Learned this from my dad, and applied it on four layouts since…)



Nobody has ever complained about having too many available outputs! I have probably 10 meters of sugar cubes under the layout, and still some outputs are shared with more than one cable…

You could also add (at least one) yellow cable and separate grounding cable to the bus, preparing for each power pack or transformer you will need for building lights etc. Of course, also add distribution plates for these cables.

Document. I mark all distribuition plates under the layout with R1 for the Central Station red, R2 for the first additional booster red, R3 etc. B1 is the common grounding cable for the CS and boosters. Y1 is the yellow feeder from the first lighting power pack etc.

Implementing a bus power system similar to this will make it easier to add switch decoders and S88 modules close to the tracks, turnouts or signals where they are required. This will limit the volume of cable spaghetti you will get anyway. And best of all, bring secure powering of your layout.