More About Data Cards

    The top card in the MFD is where you install your standby nav database.  But this card is also where your engine monitor data gets logged to.  Pop the card into your laptop reader and look for a director named ‘data_log’.  Inside of this directory will be a bunch of .csv files.  These are comma separated values files, which means it contains rows of data of a consistent format where each column is separated by a comma.  The files are named for data, time, and location.  If it cannot determine your location, the location will just blank (a bunch of underscores).  I think the only reason it can’t determine your location if you do something like fire up the system just to taxi over to the wash rack or something, and the gps doesn’t get enough time to figure out where you are.

    Ok, so what do you do with these files?  By default, your computer will probably try to open up excel when you click on a .csv file, which is worse than useless.  Excel is terrible at handling large volumes of data, and even if it weren’t, you wouldn’t get anything out of this data without some sort of visualization.

    I spent some time building a gnuplot based utility to display this engine data for me.  I sent some of the images to Savvy for analysis and they pretty quickly clued me into the fact that there’s this amazing website out there called cirrusreports.  This website is awesome.  It displays all of your engine data on a beautiful graph, and also shows your location based on your gps readings via a cute little google maps interface.  I’m blown away by what a great job they did.

    I also learned that you have to periodically clean data off of this data card.  The logs will keep getting added and there is no auto-delete functionality.  Your card will get full and then you will simply stop logging data.  I’m on mac OSX.  The first time I tried to do this I screwed it up.  I dragged the old .csv files into the trash, popped the card, and took it out flying.  I went to the AUX page and its status said that it wasn’t logging data because the card was full.  What’s that about?  Well, on OSX when you drag stuff into the trash it doesn’t actually free up the space, it just makes the files hidden.  It actually keeps references to the data on the device.  That’s how come you can recover stuff from the trash.  So, to actually clear space from the card I had to take it back home, plug it in, and select “Empty Trash” from the finder.  I can’t be the only person who has made this mistake.

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