NMRA function key defaults

[Bill H]

I heard someone remarking the other day that sound decoder x did not follow the NMRA recommended function key defaults. Took a look on the NMRA site and could not find them. From a recent article in MRH after F4, it seems that all the major sound decoders have somewhat different function key mappings. Thoughts?

[peteski]

I don't know if any of the sound or feature function key assignments are mandated by NMRA (or NEM for Europe) rules.  Maybe an exception would be the F0 key being assigned to the headlights. It seems that American manufacturers did come up with few agreed upon assignments for sounds (like whistle/horn and bell), but from what I can see, all the other features or sounds seem inconsistent.  And European manufacturers sound function assignments seem even more confusing.  Like you, I think that function key assignments (other than F0) are unregulated by the industry standard's organizations.

[jdcolombo]

There are no NMRA standards for function key assignments, not even F0.  The NMRA standards pertain only to the communications protocol, certain packet information relating to speed control over 28 steps,  configuration variables (CV's) and connectors.  See NMRA S-9.1 and S9.2 here: https://www.nmra.org/index-nmra-standards-and-recommended-practices

Basically, all the NMRA does is guarantee that decoders following NMRA standards will all use a standard addressing system and all be capable of 28-step speed control and forward/reverse direction (128 steps are not part of this standard).  You can be certain than an engine with an NMRA-compliant DCC decoder will run in forward and reverse under any NMRA-compliant command station.  And you can be sure that the decoder and the command station "speak the same language" although the vocabulary of the decoder and/or the command station might be very limited.  Like my Italian: grazie, prego, vino rosso, and six different kinds of pasta.  That's about it.

Everything else is up to the individual manufacturer.  Yes, the manufacturers have informally settled on F0 for the headlight/rear light operation; F1 for the bell and F2 for the horn/whistle, but that's about it.  Tsunami decoders, for example, use F3 for a "short whistle" sound, but ESU uses F3 for the coupler clank sound. 

I'm always of two minds when I think about further standardization.  On the one hand, it would be nice to know that F3 does the same thing on every layout I visit.  On the other hand, I like the ability to customize my function key layout to what I want, not what some 40-year-old in Chattanooga TN thinks is best.  All things considered, I'd rather have customizability over standardization.  Mostly.

John C.

[peteski]

In the early DCC days you only had few functions. Headlights, maybe ditch lights, rotary beacon or strobe, and maybe couple other lighting effects or remote coupler control. That's why many DCC throttles are designed to easily access F0-9, and any additional functions are harder to control.

This function assignment "problem" only became apparent when sound was added to DCC, and especially when the processing power and the internal memory of the decoders got powerful enough to assign some "feature" to pretty much any of the 28 functions (and now there are even  more than 28 functions.   Way too much to be useful while running a train.  Do I really need a sound of the cab door being closed or engineer's window being rolled down? 

And if you look any of the sound files for European locos on European decoders (like ZIMO, ESU, D&H or others) you will see how different even the basic lower function assignments are from the semi-standardized (by the industry itself)  American loco sounds.

[jdcolombo]

Absolutely right, Pete.

I remember that back in the mid-1990's, when I converted to DCC, all I really needed from a function key standpoint was to turn on the light.  Now . . . OMG.

But on my layout, I've cleared all the function keys except 5.  F0 turns on the headlight; F1 for bell; F2 for whistle/horn; F3 for the Mars light (when so equipped) and F8 for sound on/off.  The NKP didn't have any diesels with dynamic brakes, so I don't need that sound, though I could understand some folks wanting it, and also a key for ditch lights.  And although Drive Hold and Coast are fun to play with, in an operating session I have a hard enough time getting operators to use the horn and bell, let alone anything else (plus these days I've been running all steam anyway). 

The KISS method still works, even in model railroading . . .

John C.

[greenwizard88]

Absolutely right, Pete.

I remember that back in the mid-1990's, when I converted to DCC, all I really needed from a function key standpoint was to turn on the light.  Now . . . OMG.

But on my layout, I've cleared all the function keys except 5.  F0 turns on the headlight; F1 for bell; F2 for whistle/horn; F3 for the Mars light (when so equipped) and F8 for sound on/off.  The NKP didn't have any diesels with dynamic brakes, so I don't need that sound, though I could understand some folks wanting it, and also a key for ditch lights.  And although Drive Hold and Coast are fun to play with, in an operating session I have a hard enough time getting operators to use the horn and bell, let alone anything else (plus these days I've been running all steam anyway). 

The KISS method still works, even in model railroading . . .

John C.

I've actually started installing Tsunamis instead of LokSound decoders, because I find having to manually notch is just a pain in the behind, and Soundtraxx does auto notching based off of BEMF quite nicely, once you have it tuned correctly.

[jdcolombo]

I've actually started installing Tsunamis instead of LokSound decoders, because I find having to manually notch is just a pain in the behind, and Soundtraxx does auto notching based off of BEMF quite nicely, once you have it tuned correctly.

You don't have to manually notch an ESU diesel file.  It does so automatically, and if you want, you can adjust the notching behavior in a LokSound 5 file to your heart's content.  You do need a LokProgrammer to do it easily, however.  I personally haven't had issues with the automatic notching behavior in ESU's sound files, but you CAN "tune" it if you want.

John C.