Hello again

I've been doing some research and I've narrowed the problem down a bit.
In principle I can write CVs, sometimes I get an error message, but insisting a couple of times the writing operation gives ok.
But, I wanted to use the address 142 (the license plate number is 14282) and when I try to write 142 I get error all the time. I'm using DCC mode, and trying to write in CV(1), according to marklin documentation the address is 1 to 80 with 6021 and 1 to 255 with MS1 and 2.

In DCC you can use the range of addresses from 1 to 255 without major problem, I do it with my IB.
Well I try the option of long addresses and it is impossible to get the error message.
Then I start to test which addresses it admits, and I see that I can write in the CV(1) any value between 1 and 127, but from 128 onwards I get an error message.
Why is this? Has anyone had any experience using marklin decoders in DCC mode?
Thank you and happy new year 2019

Umm, are you sure that is using DCC addresses? You can certainly do that with MM addresses on an IB, which are allowed to go beyond the old Marklin upper limit of 80.

If you are definitely using DCC addresses then it may be that the IB is using only long DCC addresses, and your other locos where you can do this are set up as long addresses, or the IB is automatically switching between short and long at some boundary (see below)



That is correct. Long addresses can be from 0 to 10239 as Tom (H0) noted, so if you try and set 142 as a long address it will complete without error (unless the decoder had some other problem that stopped it writing).



That is normal DCC operation for a short address. CV1 only stores a short address. A long address is stored in two other CV registers AND a bit needs to be changed in another CV to switch the decoder between short address mode and long address mode.
I suspect the MS2 will handle all this automagically if you ask it to program a long address into the decoder so it is all invisible to the end user. It is possible to have a short address that is different to a long address and switch between them by changing the bit in the other CV (CV29 IIRC) without otherwise reprogramming the address.

The next trick - coming back to your claim that the IB quite happily goes from 1 to 255 DCC addresses - is that some companies making control units treat low numbered addresses entered as a loco address to select a loco as a short address, and then automatically switch to using long addresses above a certain number.

See this web page for a description of how different manufacturers distinguish between short and long addresses versus the NMRA definitions for them. I don't know at what address the MS2 switches between short and long addresses, or if it can use long addresses 127 and down. The IB may also automatically switch between short and long at some boundary other than 127/128.

A simple test is reading a CV, e.g. CV 8 (should be 131 for a Märklin decoder).
As I wrote, reading and writing CVs sometimes only works with Märklin decoders after driving the loco.

To use higher adress with the DCC you must set CV 29 bit 5 by write 1 in value.
Go to CV 17 and 18 by write value.
To set the CV 17 and 18 the locomotive must stand on the programming track.
Be sure first that the locomotives standard adress 3 must first verified in the system on the programming track before to start change the value.

The IB has a feature that sets long addresses and takes care of all relevant CVs. Thank you for pointing out a more complicated way to achieve the same effect.

Did you notice that an Intellibox was used as controller?

Per.

And the IB knows that system.
With the IB I enter the address I want in the range 128 through 9999 and the IB sets CV 17, 18, and 29 as needed.
That's the simple IB way.

OMG, why should I use a calculator to determine the values of CV 17 and CV 18 when the IB can do it for me? That would be overly complicated.

Yes, these are the wonderful decoders of the MSD era (pre-MSD/3 era).
When writing a new value to a CV, the IB will understand ERROR. If the value does not change, the IB understands OK.

I don't know if this is a bug of the decoder or a bug of the controller - but I guess it is a decoder problem.