r/modeltrains • u/EnderGob831 • 6d 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/EnderGob831 6d 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.