Drop-size data are transmitted at one-minute intervals over a RS-485 serial link (it has quite a way to go and 4-wire twisted RS-485 is a good choice). This is connected to an RS-485/RS-232 serial to USB converter (from EasySync). The USB serial device uses the standard FDTI chipset. The device appears as a standard serial port mapped to /dev/ttyUSB0.
Data logger software written in C grabs and decodes the data and logs it to file. GNUplot scripts run periodically (using cron) to generate and copy image files to the web server
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Last modified: RJW 9 May 2012