Model Railway Forum

Hello,

I'm using Withrottle with DecoderPro and a SPROG 3 to test lighting with a Hornby R8249 decoder. I've connected LEDs to the white, yellow, green and purple wires.

The first function button works fine turning either the LED on the white or yellow wires on and off depending on the direction setting.

The second function works fine turning the LED on the green wire on and off.

The third function only lights the LED on purple while it is held - on releasing the light goes straight off.

In DecoderPro all of the lock checkboxes are set against their respective function buttons - changing the second button gives the same behaviour as the third button, but changing the lock setting on the third seems to do nothing. Having a look at the XML file for the roster entry looks correct (can post if required). There's nothing configurable in the lighting tab, possibly because the R8249 is a simply beast?

Either I'm missing something simple, the decoder simply can't do what I'm asking of it, or I've got something fundamentally wrong. Any ideas?

Hi
I feel it has to be with the DCC command station and how its set up. Can you try another function button and map that to Purple on the Decoder?

Typically they are set to:
Functions 1 (white) and 2 (yellow) are preset at the factory for directional front and rear
lights. They are turned on and off with F0 or the light function and will automatically turn on
and off depending on locomotive direction.
Function 3 (also known as Aux 1) which uses the Green wire is controlled by default with
function button 1.
Function 4 (also known as Aux 2) which uses the Purple wire is controlled by default with
function button 2.

Thanks, Brian.

Judging by the relevant screen on DecoderPro this looks beyond the capability of the Hornby decoder. I think a better decoder is needed for locomotives with the full headlight compliment.

The mystery is solved - under Preferences --> WiThrottle there is an checkbox labelled 'F2 always momentary' - changed that and now F2 behaves as expected.

Why this exists only for F2 only on the WiThrottle I've no idea...

Hi
Many (if not all?) DCC systems use F2 as momentary. Converting it to Latching is usually possible. But some systems (manly older ones) don't allow this to occur!
Pleased to read you have resolved the problem and found the conversion on the system.

Mike309 wrote: ↑Wed Sep 23, 2020 5:20 pm Thanks, Brian.

Judging by the relevant screen on DecoderPro this looks beyond the capability of the Hornby decoder. I think a better decoder is needed for locomotives with the full headlight compliment.

R8249 is NMRA warranted so fully complies with their basic rules and regs. Remapping of functions is not mandatory under NMRA, hence why it is not possible on R8249.

All my R8249s have F2 (purple) as a toggle function by default.

The OP has done it already! AFAIK It is the Base unit/Command station/PC software that maps decoder function switching between Momentary and Latching, not the actual decoder.
However that said, the R8249 Hornby 4 Function decoder is very basic device and many options for adjustments and changes as per better quality one are not available.
So TBH the best option is not to use this rather expensive basic decoder at all. There are far better ones available for around the same price!