Unable to Program Hornby Class 101 Decoder

[Corsham Ed]

Hi All,

i purchased a second hand Hornby Class 101 DCC fitted with sound.

i use a digitrax dcs51 controller and I thought the train would be set to a default code of 03. Unfortunately it’s not. the person I bought the train from uses an NEC power cab and said he used a long address which he cannot remember.

can I reset the train back to a default of 03 or do I need the address from the previrus owner to do this?

any advice you have on to address this would be greatly received?

Thank you.

[96RAF]

If your controller can write to CVs then yes you can reset it back to defaults, but without knowing what make/model of decoder it is you can only use the default reset which is usually value 8 to CV8.

 

One other caution is that resetting some sound decoders can affect the sound files, which is why it is wise to know the decoder type and who wrote the sound files to it before you fiddle.

 

There is a chance the long address is the DMU number, so try a combination of any numbers on the cab side.

[Howbi]

Just read CV1, it holds the current address then write your preferred address ......HB

[Chrissaf]

Just read CV1, it holds the current address then write your preferred address.

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Unless the address is greater than 127, in which case it is a 'long address' which is not held in CV1, but a combination of CV29, CV17 and CV18.

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If it was previously configured with a long address, you could write a new 'short address' to CV1, but you would also need to modify CV29 to remove the 'long address' flag from bit 5.

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If the decoder supports a value 8 to CV8 reset, then that is the easiest way to reset all the address bits and bytes to a basic 003 short address as a new starting point. But Rob's caveat regarding 'sound decoders' applies, although in my experience that is a very low risk. To eliminate the risk completely, then read on.

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If your controller can read the values of CV29, CV17 & CV18 then you can input the values read into the 'first' calculator below and obtain the 'long address' that might be configured.

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CV29 Online calculator AND CV17 & CV18 reverse calculator.

http://www.2mm.org.uk/articles/cv29%20calculator.htm

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CV17 & CV18 Online calculator (only calculates the CV17 & CV18 values from a long address number).

https://www.modelrailforum.com/forums/index.php?autocom=custom&page=DCC-long-address-calculator

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For example, if CV29 reads a value of 38, then write 6 to CV29 and 3 to CV1 and that will give the same 003 short address as a CV8 reset. By reducing the value of CV29 by 32 (bit 5) you are disabling 'long addresses'. And writing 3 to CV1, configures the short 003 default address.

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NO.....you do not need to actually know the previous address to change it. You just need to understand the configuration relationships between CV1, CV17, CV18 & CV29.

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[Phil_Spiegel.]

No need to READ any decoder to reprogram it !  (In fact, its a lot faster not to wait for the system to read a value you couldn't care less about 8-) .. the following applies whether your programmer reads back or not:

A good first test of ANY dcc/or dc loco is to test it with a 9V battery - UNLESS 'dc running' has been disabled, this should work on either a fitted or unfitted loco !  (Forward running with +ve on the right rail)  ((except LGB))

Simply place the new loco on a programming track and write 8 to CV8  - this will reset many decoders to default. - now test the loco as No. 3  - it may,  or may not now respond.

WRITE '3' to CV1,    and '6' to CV29   to test with Loco No.3 and Short addresses (and DC enabled for 9V test)

Having established it works  - reprogram it to any number OTHER than 3, so you can buy more locos 8-)

NOTE You MIGHT wish to avoid using numbers 100-127 - DEPENDING on your controller, and whether you take the loco to visit other systems with different controllers - as in some controllers, 100-127 is considered a short address  [nmra recommendation], and in Lenz Expressnet Recommendations, it is, or was, recommended to be considered a Long address ...