Model Railway Forum

All my locos are fitted with Zimo sound decoders that I have fitted myself, and as a result all the function keys are pretty standard, which makes it easier to remember which one does what.

I have just acquired my first loco that is sound fitted from the factory, and most functions are OK, but there is one that I would like to change - the guard's whistle.

On my existing locos this is mapped to F9. On the new loco it is mapped to F13. I thought it would be a simple process of changing the relevant sound assignment CV for F9 to that for the guard's whistle and that would be job done.

Unfortunately it would appear that all the sound assignment CVs on the new loco hold a value of 0, so I have no idea how make the changes I want.

The decoder is a Zimo MS450 PluX 22.

If anyone has any ideas, I'd be grateful to hear them.

This is a very full (and complex) document for the Zimo

https://www.google.co.uk/url?sa=t&sourc ... ers_EN.pdf

It may (or may not) be helpful.

Thanks Ian. As you say, a very full and complex document. If the answer is in there, it's not immediately obvious. There is a section that mentions function mapping with a list of CVs that differ from the CVs I had down as being for sound allocation. It also mentions CV 300 procedures, though I am not sure I am brave enough to start messing about with something I don't fully understand.

I will have a look at the function mapping CV values and see if I can make sense of what they are doing. I can always reset them to their original value if they don't give me the solution I am looking for.

While I usually do not condone recommending other forums, posting your Zimo question of RMWeb sites DCC section will probably result in several replys from those in the Zimo knowledge group! https://www.rmweb.co.uk/forums/

On zimo decoders cv537 corresponds to sound file for F9 and cv549 corresponds to sound file F13

So read cv537 and write down its value do the same for cv549
Then write what value you have for cv549 (guards whistle on F13) to cv537 (F9) and then write the value you have written down for cv537 to cv549 this should swap the sounds from F13 to F9 and vice versa.

Itch45, that's exactly what I did; read the sound file cvs expecting to just be able to swap them around, which is what I have done on one or two other decoders, but all the relevant CVs on this particular decoder came back with a value of 0, which is why I posted the question.

I wonder if the decoder is locked, to unlock it you will need to write 0 to cv144. This has to be done on the main (POM) not on a program or service track and can take a few attempts. After each attempt you will need to power down the loco, just remove it from the track for a minute. After each attempt try to read the cv's to see if there is a value.
I would remove all other locos from the track just to be safe.