Cannot read CVs from R8249

[Alan K]

I have acquired a used Hornby loco with DCC fitted. I assume it is an R8249 though there is nothing printed on it to confirm that and looking at images it seems that there are various iterations with different chips on board.

It runs using address 3 but I want to change the address to match the running number. However I cannot read any CVs. I assume I cannot write either but as I would not be able to read back it doesn't seem to be worth trying.

I originally tried to read it while in the loco using Railmaster usng an e-Link (I would have tried my Elite but the programming circuit gave up and Hornby declined to repair it.). I then tried again with the decoder plugged in to a decoder tester to take any issues with wheels and track out of the equation. Further tests using a Digikeijs command station and Decoder Pro also failed. Again it would run in the tester and lighting also worked. I have had decoders fail before but thay failed completely. I have never had one work but be unreadable. Any thoughts on this would be welcome. 

[Chrissaf]

If it is definitely a Hornby decoder, then it might be the R8215 decoder that is now obsolete and was superseded by the later R8249.

 

I am led to believe that the R8215 is programmed using 'Register Programming Mode' which means that amongst other things you cannot read the R8215 CVs using any DCC controllers. Although I believe you might be able to read the 'Registers' that contain CV information using a 'Register' decoder programmer [a programmer is not the same as a DCC controller].

 

The Elite controller can write [not read] using 'Register Mode', but since you say that the 'PROG' output of the Elite is faulty, then you cannot adopt that option.

[Alan K]

The loco is DCC fitted R2625X so unless the decoder was changed it will be Hornby. 

Thanks for that Chris.

Looking at images of the R8215 as well as the R8249 there seem to be no obvious distinguising features - they look very similar. There is only one chip with a number printed on it and that number varies on both decoders and I haven't found one with the same number as my chip. 

If it is an R8215 are you saying that it is virtually impossible to write to CVs if only to change the address? That would mean that if you had two of them they would both irrevocably have an address of 3. Surely that would be unsellable (if that's a word).

...

UPDATE: Found this elsewhere on the forum,,,

...

R8215 Decoder - General DescriptionNote: This decoder has now been superseded by the R8249 4 function decoder. The R8215 is a basic 4 function decoder; it does not support the following features:1) Railcom2) Interrogation. ****Late version decoders manufactured after November 2007 have the ability to be read in “REG” mode. These later decoders are identified by a red dot painted on the MCU chip on the circuit board. Older versions of the decoder either have no painted dots, or a white paint dot.

 

,,,

Mine does have a white paint dot but the loco is not pre 2007!!

...

Apparently it is possible to write to CVs 1,3,4 and 29 but it doesn't say how.

Alan

[Fishmanoz]

As Chris intimated, being able to write CVs is pretty much independent of being able to read them.  

To write CVs 1 (short address), 3 (accel), 4 (decel) and 29, just follow the instructions in the RM manual to do it via your eLink.  Can't remember if you can have long addreess (running number?) with it is an 8215.

[Chrissaf]

That would mean that if you had two of them they would both irrevocably have an address of 3. Surely that would be unsellable (if that's a word).

 

Read my reply again. I was highlighting and focusing on the reading function separately from the writing function in my reply. Of course you should be able to write to a R8215 and change the address from 3 [see last paragraph further below], you just can't read from it .... and you were primarily querying the reading function in your post which is what my reply focused on.

 

I am assuming [maybe incorrectly as I haven't checked] that RailMaster has an R8215 writing function in it. The Elite has with its 'Register Mode' option, probably the Select has the capability to write to the R8215 too.

 

The Elite manual states that for optimum R8215 support, the Elite has to be put in 'Classic' operating mode to invoke certain firmware routines designed to support the R8215. But this could be counter-productive as 'Classic Mode' is not supported by RailMaster [RailMaster requires the Elite to be in 'Standard Mode']. Also, 'Classic Mode' could completely upset your point operations as this mode implements an offset of 3 in the points addressing scheme.

 

If you do have R8215 decoders in your loco, the best all round option is to bin them and replace them with a newer decoder.

 

In RailMaster CV Writing screen ... double click CV7 and see if the R8215 is listed in the decoder list that appears.

 

The issue is that this R8215 decoder is so old, there is no R8215 manual listed for download on the Hornby site to check its features and functions.

 

...but I want to change the address to match the running number.

 

In 'Register Mode' programming, the DCC Address is held in 'Register 1' but I believe that this 'Register' can only hold values in the 1 to 127 address range. Thus, I believe that the R8215 might not be able to be given a DCC Long Address above 127 which presumably you would need to support a 'running number' [4 digit ?].

[Rog RJ]

Reading of CVs isn't supported by the R8215 decoder and it can only handle short addresses.

 

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Sorry about the poor quality of scans.

 

[96RAF]

The info you quote is almost verbatum from my notes from way back when this decoder was current and was likely gleaned from my post.

 

This extract applies to the fairly rare ‘white dor’ version...

 

R8215 V1.2 (late 2006 - 2007)

Identification.. White dot on MCU chip.

Electronic.. Additional Zener Diode now fitted re spike protection  

Firmware.. “Runaways” Fixed Supports interrogation in “REG” mode No other enhancements.

 Issues, work-arounds and fixes..

 Known to reset to default address etc when power cycled or when recovering from an Emergency Stop.. when used with the following DCC control systems..  Bachmann EZ-Command Bachmann Dynamis Lenz LH90 Lenz LH100 ELITE 1.2 ELITE 1.3 in Standard mode  

Work around: Remove locos from layout when powering down and re-starting system.

 Fix: Replace decoder with version 1.21 or later (may apply to Bachmann/Lenz as only fix.)  Fix: Run ELITE in “Classic” mode if possible. 

 

These unreliable R8215 decoders were updated over the years and were still being factory fitted to DCC-Fitted locos long after the R8249 replacement was brought in. Hornby did offer a free replacement at the time, but I doubt they would honour that service this far down the road.