1) Turn off the power to the Arduino (or simply unplug)
2) carefully remove the SD card by pushing in until you hear a click and feel the bounce back, then pull it out, noting the wires (maybe take a picture) in case you accidentally disconnect something.
3) put the SD card in your computer and open the file. Hit save as and change the name from Datalog.txt to KathyBorgNov22Datalog.txt (This will enable us to keep backups of the old data each week and the arduino will start a new log called simply datalog.txt when it powers up again)
4) Hit "save as" again and save the KathyBorgNov22Datalog.txt file to your computer.
5) Upload this txt file to the files section of the group.
6) Replace the SD card in the arduino carefully.
7) Power it up.
If you want to make SURE it is recording well again, then before you power up the board connect it instead to your laptop and launch the Arduino program. Go to "Tools:Port" and select the port it says your arduino is connected to (just make sure it is checked and not grey).
Then go to Tools:Serial Monitor and open the serial monitor. In a few seconds it will hopefully tell you the SD card has been initialized and spit out some temp values. You can then close the program, unplug the Arduino from the computer and plug it back into power and it should record for another week. This should really be done weekly.
I have an arduino with an SD card shield reading the ds18b20 temperature probes in my digestors with a time stamp from an RTC. How do I get that data off the card and into the computer for analysis?