Strange results with Massoth decoder reading CV 29
- Thread starter Airbuspilot
- Start date
Some strange mentions of "negative" values and stuff in some of the previous posts regarding CV 29. There are no negative values used, just individual bit settings which together form a binary number in the CV byte, and then we usually end up referring to that number in its decimal form.
Using something like JMRI DecoderPro software connected to your DCC system or suitable programming hardware makes things more user friendly. I've used DecoderPro and a SPROG box for at least 10 years (probably longer) for all my decoder programming in N, HO and G.
Alternatively use an online CV29 calculator as has been suggested. Here's one which can go both ways; tick the bits you want and it shows you the CV value, or enter the CV value and click "back calc" to find which bits that value equates to.
DCC CV29 Calculator
Using something like JMRI DecoderPro software connected to your DCC system or suitable programming hardware makes things more user friendly. I've used DecoderPro and a SPROG box for at least 10 years (probably longer) for all my decoder programming in N, HO and G.
Alternatively use an online CV29 calculator as has been suggested. Here's one which can go both ways; tick the bits you want and it shows you the CV value, or enter the CV value and click "back calc" to find which bits that value equates to.
DCC CV29 Calculator
S'all very well knowing what you would like the value to be..
But the OP's original problem, is limited access to 'fiddle' and strange results (not even consistent) when trying to read the value.
My take on this, would be two decoders, or an early decoder/power-buffer. Possibly a mixture of the two?
Could be awkward to know which decoder (if either) is being changed, and to what value..
PhilP
But the OP's original problem, is limited access to 'fiddle' and strange results (not even consistent) when trying to read the value.
My take on this, would be two decoders, or an early decoder/power-buffer. Possibly a mixture of the two?
Could be awkward to know which decoder (if either) is being changed, and to what value..
PhilP
My understanding is that CV#29 is one of the few fully standardised CVs. But the defaults do differ by decoder, and some decoders don't support certain features - notably RailCom (bit 3, value 8) and (for very old decoders such as the 55021) long addresses (bit 5, value 32).
In general, setting an unsupported bit will not break anything, but it should still be zero when you read it back.
Also, every large scale decoder I have encountered treats CV#29 bit 2 as "support analog DC" rather than the more complex method specified in NMRA Standard 9.2.2.
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Actually, the reason I pointed out the chart above was not a good idea, is because there IS some deviation in CV29, note bit 6!
I made it to the railway this morning. The Loco was bought (eBay) some time ago and before I joined the group, its box shows LGB 27432 but the picture on the box has loco no 622 while this one is 619 so presumably an earlier version of the 622?
The loud noise was solved with the volume control, why didn't I think of that?
I placed the Loco on the programming track and started by reading CV 29 which came back as 34 (last time it alternated between 0 and 2). I then read some of the first few CV's, Initially all read backs were as expected giving sensible numbers in response. I read CV 17 which came back as 0 instead of 128, this also initiated the engine starting sound. CV 18 was correct reading 107, I tried CV 29 again and it came back as 0 and refused to read anything other than 0 after several tries.
Going back to the earlier CV numbers I had sensible numbers read back but random engine starting sounds with different CV selections.
The Loco runs normally but none of the functions work from my MX 32 handset, it can be used with the volume turned to Zero but it seems a shame to do that.
I have brought the Loco home and will take a look inside, assuming the interface is good I will try a new decoder.
Thanks to everyone for your inputs.
Robin
The loud noise was solved with the volume control, why didn't I think of that?
I placed the Loco on the programming track and started by reading CV 29 which came back as 34 (last time it alternated between 0 and 2). I then read some of the first few CV's, Initially all read backs were as expected giving sensible numbers in response. I read CV 17 which came back as 0 instead of 128, this also initiated the engine starting sound. CV 18 was correct reading 107, I tried CV 29 again and it came back as 0 and refused to read anything other than 0 after several tries.
Going back to the earlier CV numbers I had sensible numbers read back but random engine starting sounds with different CV selections.
The Loco runs normally but none of the functions work from my MX 32 handset, it can be used with the volume turned to Zero but it seems a shame to do that.
I have brought the Loco home and will take a look inside, assuming the interface is good I will try a new decoder.
Thanks to everyone for your inputs.
Robin
That looks like a 28434. If so, and you don’t have a copy of the manual, this link should get you to a downloadable version
It‘s been a while since I did any CV work on a GE 4/4 II but I vaguely remember some posts about issues with the capacitors in the sound module interfering with CV reading/writing. I think the recommendation was to “drain” these before attempting to do any programming or, failing this, to disconnect the sound module from the decoder. More worthy folk than I will probably confirm if my memory is right/wrong. Apologies if you’ve already been down this road.
It‘s been a while since I did any CV work on a GE 4/4 II but I vaguely remember some posts about issues with the capacitors in the sound module interfering with CV reading/writing. I think the recommendation was to “drain” these before attempting to do any programming or, failing this, to disconnect the sound module from the decoder. More worthy folk than I will probably confirm if my memory is right/wrong. Apologies if you’ve already been down this road.
Thanks Phil, I have downloaded the manual.
I don't know what I'm going to find inside when I open it up, if it has a separate sound decoder I will disconnect and try again. I don't want to replace a decoder unless I have to.
Robin
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According to the manual linked to above, you can set the "Mode of Operation switch" which is inside one of the cabin doors to position 2. This will power the motors, lights and pantographs - but not the sound. I would try that first and check if CVs can be read consistently. Reset the switch to position 3 after programming to allow for sound effetcts.
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Thanks, thats a good idea. I will not be able to see the railway until next week, as I have the Loco at home I will take it apart to see what I am dealing with but will do as you suggest before trying to change decoders.
Robin
Good point. I was advised by a very wise G scaler some years ago that it was good practice to always turn off locos that are fitted with on/off switches at the end of each running session. That way, there was never any risk of putting a “live” loco onto powered tracks and causing hiccups in the electronics. (Appreciate the risk may be small but my view is why take a chance for the sake of flicking a switch.)
I generally do my programming with the switch in the 1 position - typically power to motors only - and this approach seems to work ok.
I finally managed to open up the Loco, it has 3 "decoder type" circuit boards, two on the main chassis and one in the roof of the cab. The four wires from each motor block goes to the unit in the roof. The smaller of the two chassis mounted units is connected to the speaker. The manual has a page showing the board layout and connections so presumably this is "as delivered" by LGB. I have no idea what these boards do and my thoughts for a decoder change are now well beyond my current capability. I am assuming this is quite an old Loco as presumably a new one would only need one board?
On Monday I will try to read CV's with the selector in the No 2 position to disable the sound.
As a decoder change isn't on the cards it looks like silent running for some time, unless there is a way to stop the engine noise on power up.
Robin
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On Monday I will try to read CV's with the selector in the No 2 position to disable the sound.
As a decoder change isn't on the cards it looks like silent running for some time, unless there is a way to stop the engine noise on power up.
Robin
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To my eye the little red pip on the sub board in the first 2 pictures looks to be a volume control. Try it see. Or is this what you found in post 26.
As for the looks of the rest of it, if it is indeed a 28434 (and 619 Samedan would appear to confirm that) then what you have is a 2011-12 produced Sound Loco with On-board decoder. Thus those 3 boards will all be part of the DCC and sound for the loco as shipped.
Wondering if a reset to as bought new configuration would sort it?
What does anyone else think?
If that works, you would the only need to set CV1 to be other than 3, for my money I would make it 19 as the last 2 numbers of the actual loco a system that tends to work unless you have a massive fleet.
As for the looks of the rest of it, if it is indeed a 28434 (and 619 Samedan would appear to confirm that) then what you have is a 2011-12 produced Sound Loco with On-board decoder. Thus those 3 boards will all be part of the DCC and sound for the loco as shipped.
Wondering if a reset to as bought new configuration would sort it?
What does anyone else think?
If that works, you would the only need to set CV1 to be other than 3, for my money I would make it 19 as the last 2 numbers of the actual loco a system that tends to work unless you have a massive fleet.
Ok so you have:
1) Large LGB Onboard decoder (the one with the Red socket on it - right hand side of the second picture)
2) A Sound module (left hand side of the second picture)
3) Pantograph control board and power selection (track or overhead) - 3rd picture.
I suspect that the sound board is actually a DCC decoder. Note it has 2 wires coming 2 pins at the bottom centre going to 2 pins in the centre of the Large Onboard decoder.
These pins provide track power from the decoder. I would suggest disconnecting this cable (temporarily) and try to read (and possibly change) the CVs you require.
1) Large LGB Onboard decoder (the one with the Red socket on it - right hand side of the second picture)
2) A Sound module (left hand side of the second picture)
3) Pantograph control board and power selection (track or overhead) - 3rd picture.
I suspect that the sound board is actually a DCC decoder. Note it has 2 wires coming 2 pins at the bottom centre going to 2 pins in the centre of the Large Onboard decoder.
These pins provide track power from the decoder. I would suggest disconnecting this cable (temporarily) and try to read (and possibly change) the CVs you require.
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Firstly thanks to everyone for the help and advice.
I have selected the cabin switch to sound OFF and the CV’s read normally. I set CV 29 to 34, to ensure DC was OFF, but left the others unchanged.
With the switch in the sound ON position I still have the same problem, engine start sounds with power up and when running. I have no light control and no other functions.
Jon suggested reverting to factory settings, the manual said to set CV 55 to 55 which I have done. CV 1 now reads 8 and the long addresses 17/18 are still there. Reading through the other CV’s they were all unchanged except CV 6 which went from 32 to 160?
If I have read the manual correctly I assume I should have seen CV 1 as 3?
The Loco runs fine but I have sound OFF until I can figure out what needs to be done.
Robin
I have selected the cabin switch to sound OFF and the CV’s read normally. I set CV 29 to 34, to ensure DC was OFF, but left the others unchanged.
With the switch in the sound ON position I still have the same problem, engine start sounds with power up and when running. I have no light control and no other functions.
Jon suggested reverting to factory settings, the manual said to set CV 55 to 55 which I have done. CV 1 now reads 8 and the long addresses 17/18 are still there. Reading through the other CV’s they were all unchanged except CV 6 which went from 32 to 160?
If I have read the manual correctly I assume I should have seen CV 1 as 3?
The Loco runs fine but I have sound OFF until I can figure out what needs to be done.
Robin
CV1 should indeed have reverted to 3 on a reset, I am as baffled as you now. Pity you are not close to where I live as we could have tried doing things on my old LGB Parallel set up that I retain for just updating CV’s on my older LGB lokies.
Erm, probably a dumb question but did you turn the cab switch back to sound off before you issued the reset?
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Not so dumb a question, I think so but you have me wondering. I’m fairly sure after finding the situation was unchanged I turned the sound off again but I need to go back and have another look to be sure. Thanks for pointing this out.
So your post says after following the first 2 suggestions (some other device is on the rails interfering with reading the CVs, that has been confirmed), good.
(you were finally communicating with the motor decoder)
Now you are trying to work on the sound decoder... right?
If the sound decoder is programmable, you have no way to isolate with the switch, does that make sense? You can have the motor decoder ONLY (by powering off the sound), but if the sound decoder is really a decoder, you CANNOT talk to it "only", there is no "sound only" switch position is there?
As Mark said, it appears the sound decoder is fed from the track, thus it MUST be a DCC decoder. You need to disconnect it, and connect it only to the programming track (and of course have the manual).
(this could be done externally with decoder lock I suspect, but I don't think that is a good option right now)
Greg
(you were finally communicating with the motor decoder)
Now you are trying to work on the sound decoder... right?
If the sound decoder is programmable, you have no way to isolate with the switch, does that make sense? You can have the motor decoder ONLY (by powering off the sound), but if the sound decoder is really a decoder, you CANNOT talk to it "only", there is no "sound only" switch position is there?
As Mark said, it appears the sound decoder is fed from the track, thus it MUST be a DCC decoder. You need to disconnect it, and connect it only to the programming track (and of course have the manual).
(this could be done externally with decoder lock I suspect, but I don't think that is a good option right now)
Greg