Re: Buffer mode and logging not working at the same time: You’re right, this is an edge case that’s not handled in the firmware. When buffer mode is on, the meter skips calculation of the mean or RMS value, and those are the only values that the logging task checks. I think the right behavior for now is for the logging to go silent in buffer mode. If I get some more development time down the road I could probably make it spit the waveforms in to the logfile, that could be useful to some. But you’ve found another bug, thank you :)
Re: logfiles with headers and no content: I think I’ve addressed this and will be pushing the update ASAP (in upcoming release 25). In version 24 and prior, a new logfile is created as soon as the SD card is available, whether or not the user has activated logging. This is not a good behavior and has been changed.
Re: stability – your feedback has driven a lot of good changes, thank you again. “Sure are a lot of variables” – this is frighteningly true. The poor little 8051 core with 8k ram is being pushed to its limit. There are two other changes in the upcoming release that I think you’ll appreciate: first is that log settings are saved to nonvolatile memory, so that if the meter somehow accidentally reboots while logging, it will resume logging with the same settings as soon as it recovers. Second, I discovered that the waking of the SD card and the sleep/standby of the SD card could be out of sync. That might seem like a strange error, but it stems from the fact that the ADC and the SD card share a power supply. So the firmware bundled with release 25 should be even better.