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25 Posts
Discussion Starter · #1 ·
As mentioned previously, I have an LGB 28002 with an after-market Massoth eMotion L decoder.

Mostly, this all got up and programmed fine. However, the sound/smoke interface on the LGB 28002 seems designed to work with LGB "serial mode" only.

CV 49 is set to 2 (parallel only, Digital load control). CV 54 is 1 (switch A1 with F1), CV 55 is 0 (A1 steady on), CV 53 is 32 (100% track voltage).

If I program the Massoth to operate in parallel mode only (CV 49 bit 0 off), I can trigger the LGB 28002 interface by manually triggering F1 multiple times in a row (with gaps of a little less than a second). On for option 1 (whistle). On-off for option 2 (bell toggle). On-off-on-off for option 4 (sound on/off toggle). Etc up to 8!

Issue: I say 'on-off' because both JMRI DecoderPro and my z21 handset app seem to want to latch the F1 interface button - I can't figure a way to get them to send F1 and then have the UI revert (but don't send F1 again on release).

Issue: I can't tell if the smoke generator is correctly turning on and/or off. Sounds play as expected, but there doesn't seem to be a "smoke on" indicator light, so I don't know if the smoke generator is not turning on, if I haven't fuelled it correctly, or if it's somehow mis-configured or broken.

What I'd really like is to be able to program the eMotion so that it accepts regular F-commands (f1-f8, or anything appropriate) to trigger the 28002 sound unit. This probably means accepting regular F-commands and translating to serial pulses out A1. I can't figure out how to make either the Z21 app or JMRI send serial F1 commands on the track, and don't particularly want to.

I spoke to Massoth tech support, and while helpful they seemed to be consistently describing how to make a "serial" interface work between my controller and the decoder. I want that interface to be normal ("parallel"), and have the decoder convert to serial pulses out A1.

Massoth CV49 does have two functions related to serial/parallel. Setting bit 0 to 1 enables auto-detection of serial/parallel F-keys. Setting bit 3 to 1 (8) enables "Fast pulse string (P-update) on A1", but I can't find any documentation about what this actually does. If I set fast pulse string (and make no other changes), my existing setup stops working.

I think Dan has mentioned that some of the Zimo decoders can handle parallel (DCC input) -> serial (output) translation, but I can't seem to find any stockist for large-scale Zimo in Australia.

(Note on "single" / "once" - I believe the NMRA standard suggest sending each command multiple times to compensate for lossy transmission. I assume there's a timeout so that decoders can tell the difference between repetitions and new instances of the same command.)

  • eMotion L
    • Is it possible to configure an eMotion L to map standard F-keys to pulses out A1?
    • What does CV49 bit 3 actually do?
  • LGB 28002 sound controller
    • It seems that this works by watching for polarity changes (on/off) across A1, with some sort of timeout. Is this correct?
  • Controllers
    • Is it possible to configure JMRI DecoderPro or the z21 app to send serial pulses (to a specific loco only)?
    • Is it possible to configure JMRI DecoderPro or the z21 app F1 button to "push to pulse"? That is, sends a "single" pulse but then returns to the "off" state in the UI.
    • The z21 F buttons can be configured as "switch", "push button" or "time". I can't find documentation on the difference between these options. Only "switch" seems to work for me, and appears to send the appropriate F-key "once" each time it is toggled.
  • Zimo
    • Is there a model of Zimo decoder that can accept regular F keys and generate different pulse counts out a single output based on F-key?
    • Where would I source one (including the adaptor for the LGB 55020 interface) in Australia?
  • Smoke generators
    • Is there an easy way to tell if a smoke generator is "on", other than waiting to see if it starts smoking?
  • Is there a better forum to ask these questions?

Premium Member
4,101 Posts
It is the hand set (MX32) from Zimo that is used to send serial commands. The MX32 remembers speed step settings and serial output for individual engines, it is not the Zimo decoder which only gets the speed step configuration.

Super Modulator
21,432 Posts
So reading the post in sequence, yes, since F1 is normally the bell, it is a toggle/latched.... press once and the Throttle tells the Command Station to send the F1 on command.

Press again and the Throttle tells the Command Station to send the F1 off command.

This is how the bell sound is typically used.

I don't know the configuration stuff to change F1 from latching to "momentary".... My NCE system can do this, my Zimo system can do this. There is almost undoubtedly a way to do with with JMRI, cannot comment on the Z21.

Next you talk about not being able to verify the smoke generator. I would suggest that you test the generator to know it works (apply power somehow), be sure you know how much to fill it, and not over fill, and then observe the operation. If you want a "indicator light" it might be possible to program the decoder to trigger a function output when the smoke unit is enabled... it would only show that the "command" had been sent to the smoke unit, assuming programming is right. I don't think this is very practical.

Looks like CV49 lets the DECODER try to interpret if it is being sent parallel or serial commands. Interesting, wonder if it works.

I have a Zimo system, I cannot set it for serial functions, that menu is grayed out.

On your questions:
Maybe CV49 will accept parallel commands, but you start the post saying that the decoder does NOT accept parallel commands. Are you sure CV49 does anything for YOUR decoder? I suggest that this level of detail might best be answered on the GScaleCentral.com forum, many more experts on Massoth there.

LGB28002: Here is a helpful thread on Gscalecentral.com :
apparently pretty old and originally came with a very early MTS decoder, so, what smoke unit and how connected? Did you talk to who installed the unit?

I answered about setting the controllers for serial, I would consult the JMRI and the Roco forums.

All Zimo decoders available now are parallel only on functions (correct me if I am wrong Dan).

Smoke on? If this is a simple heater, do as I said before, find a way to test (apply power separately) and verify. You could also put a voltmeter on it to see if power is applied (again if it is just a simple heater style).

Yes, better forums, Massoth questions on Gscalecentral.com, look up and find the roco group... JMRI is on groups.io


25 Posts
Discussion Starter · #4 ·
Thanks for that.


The LGB 28002 has an LGB 55020 socket, but no DCC decoder. Attached to the A1 interface of that socket (on the LGB 28002 side) is a secondary "sound decoder" that activates the built-in sound & smoke functions when A1 is toggled.

The eMotion L DCC decoder is pin-compatible with that socket.

Toggling A1 via F1 lets the DCC decoder 55020 / 55021 / eMotion L / <insert decoder here> transmit serial F1 commands to the built-in "sound decoder" interface. Technically the decoder is acting as a "buffer" of sorts, since it accepts the DCC F1 signal, toggles A1 in response to that, and then the "sound decoder" interprets that.

Questions about smoke generators are because I had my smoke generator working once on the LGB 70255 loco, but can't get it working again, nor on the 28002. So I'm trying to tell whether the smoke generators are not working because:
  • It's broken
  • I'm not applying (enough) power
  • I haven't actually turned it on (or have turned it back off)
  • I've over-filled it (or under-filled it)
So I was hoping to restrict the options by checking whether the loco thought that the smoke generator should be powered. I might have to take the cases off and poke around with a voltmeter.

I suspect I'm out of luck on finding a decoder that can translate F1-F8 into 1 to 8 sequential toggles of A1.

Thanks for the guidance. I'll poke around and see what I can find.

Super Modulator
21,432 Posts
OK, so you have not answered if the smoke unit is stock or different from the install.

If it is the stock unit, then it is a simple heater. You need to find what voltage it runs. Then disconnect it from the decoder and apply that voltage separately.

You can find information on how to fill it, turn it over, empty it, and add the recommended amount of smoke oil, that answers the overfilling/underfilling question.

Then after you have verified it works at the correct voltage, connect back to loco, put on rollers, get a voltmeter to check the voltage to the unit, and try to turn on and off and see if voltage applied, this tests the decoder operation and verifies the function key needed.

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