I also changed the format of the logging file from column delimited text to CSV (Comma Separated Values) which just makes importing into a spreadsheet a little bit simpler.
I have been tinkering with a couple of op-amps to make a 'prescaler' for the temperature sensors. A voltage reference of about 2.6v-2.8v (adjustable) is subtracted from the Kelvin value voltages from the sensors to give an output that is closer to Celcius values. Gain of the differential amplifier is also set at x5 so 10-90 Celcius gives almost a full 5v swing to the input of the digitiser.
In order to get a better accuracy (smaller steps) I have also decided to invest in a different board to try as part of the Datalogger package. The new board is the Tronisoft DACIO 300. 8 Analogue inputs and two 8 bit digital IO ports, all connected to the computer via RS232. I have used this board before in another project so I'm comfortable with it.
The downside is that it needs a COM port, so I'll need to use a USB>RS232 dongle on the laptop. This slight disadvantage is more than made up for by the extra capability and resolution of the new board.
Possible expansion of the logger may include indoor and outdoor temperature sensors, monitoring of the solar panel and battery voltages and some other monitoring functions.
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