LGB 23252 with 55021 Decoder Serial / Parallel Question

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R. Wolfe

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Hello, I have an older LGB 23252 Columbus Forney with sound which accepts an optional LGB 55021 Decoder that plugs directly on top of the board. I added the decoder 15 years ago and have not run the older DCC it in over 14 years. I have recently started using an MTSIII with Massoth navigator and have been running much newer equipment which operates in parallel. What do I need to do to make this older Locomotive functions work in Parallel as I can't stand the old Serial method? Is it a matter of a decoder change, a CV change or scrap the entire electronics for a New Sound Decoder? I like the sound system and hate to remove it but the serial thing is not for me. Thanks, Richard
 
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Greg Elmassian

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Well, first you will want to get the version number (CV7)

version 2.3 and above will support 28/128 speed steps, otherwise you are locked in to 14 speed steps, so you need to set your system to send the appropriate commands.

CV49 will change between serial and parallel: go here are read on the 55021


Greg
 

R. Wolfe

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Greg, great information. What a huge help. Thank you!
 

Andrew_au

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There are a few different combinations here and what you need to do depends on the combination.

Quick technical explanation:

LGB decoder control:
  • "Parallel" mode is standard DCC control. DCC controller tells the loco to "Set a F-register to on/off" (e.g. "Set F3 to on"). Registers go from F0 (lights) to up to F8 or F16 or even F28 or so, depending on how many your decoder supports.
  • "Serial" mode is an LGB hack. Rather than use F2..F8, the controller toggles F1 some number of times. Typically, this toggles F{x}, where x = number of times F1 toggled. Rate of F1 toggling is about 1 per second, with a longer gap indicating the end of the sequence.
Your decoder will almost certainly support proper "parallel" operation. Some controllers support "serial" (or "F1 pulse", which is a better name) mode. Unless you need to interoperate with very old LGB control systems (MTS I or II), just use standard ("parallel") mode and be done with it.

Where all this becomes more complex is once we start dealing with LGB sound boards. With many of the old locos, F0 controlled the lights and everything else was controlled via the sound board, implemented by piping F1 directly to A1 (the sound board interface). So now there is a truly "serial" connection between the decoder and the sound board. Actually, it usually ends up as a serial connection between the controller and the sound board, proxied by the decoder (which just toggles A1 to match F1).

There are a few options to drive these sound boards:
  • If your controller supports "F1 pulse", then you can set this mode for this loco and the controller will convert F1-F8 into an appropriate number of pulses, which will then toggle F1 on the decoder and thus toggle A1 for the sound board to read. This works fine as long as you have a controller that supports it and make sure you don't use F1-F8 to drive any actual outputs on the decoder.
    • Trick: in this case, you are better to set the decoder to "parallel" mode and just let it proxy F1 to A1. If you need to drive A2 or other functions just make sure you set them to be driven by F9 or above.
  • If you don't mind pain, you can manually toggle F1 on the handset (and count the pulse and make sure you toggle it about every 0.75 seconds). It should also be possible to script this behaviour, if you can find a handset to support it.
  • Finally, some decoders offer an option that can convert signals F1 to F8 into toggles of A1. This allows you to use a standard handset and the decoder maps regular F1..F8 commands into the A1 pulse / "LGB fast pulse" behaviour. But see below.
Decoder support for A1 pulse emulation:
  • Massoth decoders designed to fit into the LGB 55020/55021 pins (eg eMotion L) offer "fast pulse" mode. This toggles A1 very quickly (less than 0.25s), while some of the older sound boards (e.g. LGB 28002) require a toggle rate much closer to 1 second. Also, the eMotion series have an odd "feature" where you can't enable A1 pulse without also enabling serial mode emulation (translate multiple incoming pulses of F1 to F1-F8).
  • On my DRIVE-L, I need to make sure I don't toggle F1-F8 again why the decoder is processing the first request or the second signal is lost.
  • Zimo MX large scale decoders offer "pulse chain recognition" (CV 112, bit 4) and "pulse chain generation" (CV 112, bit 7). Pulse chain generation is what you want, but I couldn't get an answer out of Zimo tech support about the pulse rate. The newer MS series are not documented as supporting either form of LGB pulse chain.
Conclusion

Options:
  1. Use a standard decoder and a controller that supports "serial" mode
  2. Use a decoder that supports "A1 pulse" mode and figure out how to configure it correctly for your sound board.
  3. Rip out the LGB electronics and replace them with a standard sound decoder setup.
 
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Greg Elmassian

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andrew, he states in the opening post he has an MTSIII system with a massoth navigator, so all the talk about different systems is moot.

He's not going to have trouble sending parallel commands (besides the fact he asked how to set up the decoder for parallel), that issue is also moot. It's already certain that the 55021 supports parallel... maybe you did not observe the link I posted and the OP read..

I suppose that the mtsIII and Navigator combination will support serial (there I'll leave it to the experts), clearly the MTSIII and the stock throttle does support serial and parallel.

But indeed the question is what happens with the sound board if you switch the decoder to parallel.

Clearly the rest of the conjecture about changing decoders and what systems support what is also moot, if he changes decoders he's not going to have issues since he has the MTSIII and the Massoth Navigator, and he'll pick appropriately.

Greg
 

Dan

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The 55021 controlled the motor, front and rear light, plus F1 for voltage via CV 49. Unfortunately the voltage was a number between 1 and 32. LGB suggestions for CV value is very dependent on track voltage value. My system has 24 volts on the track so the suggested numbers are too high. Others may have 16 volt track voltage and the numbers will be too low!!!
 

LGB333

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Hello, I have an older LGB 23252 Columbus Forney with sound which accepts an optional LGB 55021 Decoder that plugs directly on top of the board. I added the decoder 15 years ago and have not run the older DCC it in over 14 years. I have recently started using an MTSIII with Massoth navigator and have been running much newer equipment which operates in parallel. What do I need to do to make this older Locomotive functions work in Parallel as I can't stand the old Serial method? Is it a matter of a decoder change, a CV change or scrap the entire electronics for a New Sound Decoder? I like the sound system and hate to remove it but the serial thing is not for me. Thanks, Richard
Hello R.Wolfe - Using the LGB MTS III with the Massoth Navigator gives you full access to Read and Write DCC decoders' CVs, and as already indicated, both Parallel and Serial functions control. If you have a problem getting your older LGB 55021 to work in Parallel, then you could install a replacement Massoth L Locomotive DCC Decoder as shown below on my Website. The hard part is the removal of the smokebox, boiler and cab to get to the circuit board as you may remember from 15 years ago!

The factory-sound isn't bad on the LGB Forneys produced by the former LGB company, but if you want outstanding sound, you might want to remove the factory main board and the sound board in the water bunker and replace them with one of the current DCC sound decoders which have superior sounds and features compared to those sound boards. There's a demo video on my Website of a LGB Forney produced by Marklin in 2014 that has the Interface for a 28-pin push-in DCC Sound Decoder and it has the Massoth XLS-M1 DCC Sound Decoder I installed with their Forney Sound File loaded.......sounds good. But if you want to have one of the very best DCC sound decoders currently on the market, I install and sell the ESU 5XL DCC Sound Decoders. ESU has one of the most extensive sound file libraries and most sound files are great with 30 F Key functions.......check out the demo video on my Website of an LGB Uintah Mallet Steamer with ESU 5XL installed......the chuff sounds recorded from a real 2-6-6-2 Mallet steamer are fantastic.

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