Model Railway Forum

Morning my name is Neil I have a digitrax DT 500 now I all so have now a Hornby TTs class 31 the function buttons don't seem to match the the loco or am I missing something anyone any where.

Decoder manufacturers do not have to follow a set series of CVs/F numbers for specific functions, except the basic ones such as F0, F1 and F2 But even here it depends on whether sound or non sound decoders are used. FO is usually Lighting On/Off but then its begins to get cloudy! Non sound will use F1, F2 F3 and F4 for the first four functions where a four function decoder is being used, but on Sound decoder F1 frequently becomes Sounds On/Off and then the manufacturer will decided what sound is attributed to what F number. Some decoders allow the user to alter these others are locked.
The same also applies to CVs... such as CV 1 - Address number. CV2 Start Volts. CV3 Acceleration rate. CV4 Deceleration rate. CV5 Top speed and CVs 7 & 8 Decoder manufacturers spec. and CV reset. All the reset can be whatever the manufacturer wants them to be.
The NMRA do offer guidance on these but its not all mandatory

Thank you for your help is it possible to change them or do I just write a list for each decoder.

Hi
My post above was being updated and corrected when you replied. So it may be worth reading it again?
Some decoders can be remapped but not basic/budget ones such as the Hornby TTS or their basic non sound decoder

Thanks again what sound decoders would you use I have Bachmann locos except for the Hornby TTs class 31. I have ordered a 21 pin sound decoder from Howes models I hope it will be okay.

Are you sure the loco you're putting it into has a 21 pin socket?

Your original post was about a Hornby Class 31 with TTS decoder, that is an 8 pin decoder.

The paper work which came with it says it has I've not had the body off yet .

Bachmann tend to use 21 pin in their larger diesel locos. The box usually has 21 or 8 etc on the end flap. The locos manual will also specify the decoder type too. Hornby TTS is 8 pin.

If budget isn't too important then look at the excellent Zimo range or ESU Loksound.

Both Hornby 31s are 8-pin, the plastic chassis railroad style one and the heavier all wheel drive mainstream one. TTS benefits from a speaker upgrade.
Edit - download the 31 TTS user manual if you don't have it. The decoder is hard written with the sounds allocated as listed in the blurb and cannot be remapped.

Thank you all for your help.