LGB CVs and Functions


29 Nov 2020
San Diego
I understand the CVs on modern LGB Massoth decoders are consistent (in that there is documentation on the LGB website with a CV list), but as far as I can tell, the default function mapping does not have that same consistency. I know decoder companies like SoundTraxx/TCS/ESU publish their default function mappings, but LGB does not.

Firstly, can someone please confirm for me that this is the case? That is, there is no published list of default function mappings for Massoth/LGB.

Secondly, are there any "core" functions that tend to be consistent on these decoders. ie Can you generally count on the fact that the horn, bell, coupler etc will be mapped to a specific function number by default? If so, could someone please list those here?

Thank you.

Greg Elmassian

8 Mar 2014
San Diego
I think you need to get the actual documentation on the specific decoder you have.

Secondly: no, not completely consistent for your list.... I believe all you can count on is lights, horn, bell, but there seem to be different startup commands to even get sound.

I will defer to the experts, but reading between the lines, is your idea to establish a standard mapping on your railroad?

If so, my suggestion would be to search out the decoders you have that CANNOT have their functions remapped...

Then throw them away err... try to use them as your baseline, and remap your more modern decoders.

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Neither idle nor a marvel
13 Jul 2015
I don't remember seeing a list of default function key settings, but in general these apply to LGB/Massoth decoders:
0 lights
1 whistle/horn
2 bell
5 side cylinder (steam) engine startup/shutdown (diesel)
6 engine sound
7 smoke generator
8 shunting speed

3 and 4 vary sometimes conductors whistle, station announcements, coupling sound, coal shovelling sound, etc.
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Greg Elmassian

8 Mar 2014
San Diego
Since you (gigasaurus) are in the USA, you will find that in the US, and most modern decoders have F8 as mute or sometimes "startup"..

My Zimo decoders all have F8 as sound startup, the rest of my decoders use it as mute

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Phil S
11 Sep 2015
Ann Arbor, Michigan
I've only got two locos that came with LGB MTS decoders made by Massoth, both Swiss electrics. (ABe4/4 and Ge 6/6 I). There are some function assignments that are consistent.

Lights (of course!)
F1 : Whistle
F2 : Brake sound
F4 : Station announcements
F6 : On/off for standing and operating sounds
F8 : Sound On/off


3 Jan 2010
the default function mapping does not have that same consistency

if you are talking about "sounds", why would you expect them to? Steam/Diesel/Electric locos all haver their own specific requirements (coal shovelling for an electric loco?) and it would be silly to "waste" a function number because that sound isn't appropriate.

For sound decoders "bought loose" (for self installation) Massoth recently (20th November) announced that they had added a complete list of sounds and datasheets to their website (though the links to the PDF datasheets are causing them a problem, at present) at Soundprojekte für XLS, XLS-Onboard, XLS-M1, LS, S, S PluG – Massoth Elektronik GmbH but, once the datasheets are available again, the ones for a specific loco show (in two sections) the function buttons for the "standard" sounds, and those for the "Special functions". Here is what the one for "Heidi" shows . . .


However, a word of caution. I bought a "Heidi" with factory-fitted sound new in 2006 (my only LGB loco with factory-fitted sound) when I believe the digital chips were made by Massoth, and the allocation has significant differences . . .

F1 - Whistle, signal on open line
F2 - Vacuum exhauster, brake sound
F3 - Whistle signal with echo
F4 - Conductor announcement
F5 - Boiler sound off/on - when turning on, coal shovelling is heard
F6 - Water jet blast
F7 - Steam generator off/on
F8 - Sounds off/on
F9 - lights off/on

(before contradicting itself in a second list, in the "advanced users" section)

. . . but remember that whereas an LGB handset only allows 9 functions, a Massoth Navigator offers around double that.

Of course, your initial message referred to "modern LGB Massoth decoders" and, in anything I consider to be "modern", the decoders are not made by Massoth.

I don't know if my contribution helps or hinders the debate. In time-honoured tradition, I'll just point out that it could be worth exactly what you paid for it!

All the best

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Greg Elmassian

8 Mar 2014
San Diego
I don't think it is unreasonable to standardize sound functions on your railroad.

I have done the same, and I have all 29 functions available on all controllers

But it is unreasonable to expect you can remap old decoders to match an arbitrary custom configuration

Like I said, start with the ones you cannot customize, and customize the rest to match. If you run steam and diesels, be prepared to use about 20 functions since as 7 of diamonds pointed out, steam and diesel will not completely overlap, indeed hardly at all....

automated horn/whistle crossing sequence
coupler couple/uncouple
momentum (usually nice to have on function button, maps to "train weight")

That's about all in common... although some decoders might allow you to do doppler shift on the horn/whistle like my QSI decoders, and simulate heavy loads (usually momentum setting is enough)



28 Jan 2010
Eastern MA
THe older LGB decoders (55021 and 55027) do have standard features and have manuals.
The onboard decoder does have standard connections but cv's are preprogrammed differently. CV 106 is the number for the factory load on these decoders.
Unitah mallet is 129
American trolly is 146
Coke Mogul is 129
F7 is 146
Mystic porter is 73 this is a smaller 1 motor on board decoder
65003 208
In summary, it appears that American steam locos with the 2 motor board has 129
American 2 motor diesels/electric are 146
Track cleaner loco 148
small single motor porters are 73

Greg, feel free to add this info on your site, I do not think many people know about this.