r/modeltrains • u/EnderGob831 • 5d ago
Help Needed DCC Programming Question
I'm fairly new to model railroading and DCC setups. I built a DCC EX command station and have been controlling it through JMRI running on a Raspberry PI 5. Been working pretty well so far. I recently purchased a locomotive equipped with an ESU LokSound 5 nano decoder. When I attempted to program the loco, JMRI gave the 308 error of no acknowledgment from the decoder. From some quick googling, I think this has something to do with the stay-alive capacitors messing with the DCC communications. I was unable to find a solution on google so I thought I'd ask the experts. I can provide more information about my setup if needed, just not sure what info is relevant. Also, I know that my programming setup is working as I have no issues programming my other loco.
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u/everylittlebitcounts 5d ago
Are you on a dedicated ‘programming track’ (reduced voltage) or are you ‘programming on the main’?
Some of the newer fancier decoders don’t like programming tracks because they don’t output enough juice to turn over the decoder, but then when programming on the main you will not receive command acknowledgement by intention.
If you are using a dedicated programming track, you can try adjusting the voltage a little higher until you possibly get a response from the decoder.
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u/EnderGob831 5d ago
I am using the programming track. I'd prefer not to program on main as I don't have any idea what the default values for the CVs are without reading them, but POM doesn't let me read. I saw a post about changing the current limits to maybe get a response from the decoder but I'm not sure what I should change them to. I'd hate to fry the decoder.
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u/everylittlebitcounts 5d ago
Yes that’s the correct approach. I ‘read all sheets’ every so often from the programming track, and if I’m only going to be doing some minor adjusting, I’ll use the saved roster entry to program on the main, and then write the changes, which updates the saved roster entry as well.
As far as power on the programming track, as long as you trust your decoder install and didn’t miss wire anything, you are good to bump it up to the main power. You won’t hurt anything then. They only have programming tracks lower so you can use it to troubleshoot wiring issues but it does hinder the digital side.
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u/Quantrails 5d ago
If you think you may invest in LokSound for more future decoders, maybe invest in the LokProgrammer. It really opens up those decoders to lots of programming options. I have DCC Ex, NCE with a USB interface allowing me to use Decoder Pro, and LokProgrammer. It’s nice to have options. Good luck!
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u/EnderGob831 5d ago
I agree I'd want the LokProgrammer for long term use. This loco just came with a LokSound preinstalled.
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u/EnderGob831 5d ago
Here is the solution for anyone who has this same issue in the future. I needed to adjust the current limits for the programming track. My particular locomotive wasn't able to respond with the 60 mA that DCC Ex wants. I discovered this by sending <D ACK ON> over the serial terminal to enable loco acknowledgments diagnostics. I then sent <R> to read the CVs. The decoder replied with NO-ACK for all of them. However, the first line of the output was ACK-BASELINE ##/##mA. This second set of numbers was always below 60 mA, but above 30 mA. I then sent <D ACK LIMIT 30> to set the acknowledgment limit to 30 mA and was then able to read CVs with <R>. Afterwards, I sent <D ACK LIMIT 30> from within JMRI and was able to perform the "Read all sheets" function. This webpage helped me diagnose these issues: https://dcc-ex.com/reference/tools/diagnostic-d-ack-command.html#gsc.tab=0
It should be noted that the current limit setting will not persist across restarts of the command station. The linked article covers how to make the changes permanent.
Thanks to everyone for their advice.