Serial Voltmeter
I built this serial voltmeter a few years ago and used it to measure the voltage of my solar system every five minutes. It has since be replaced by the built-in monitoring hardware of the Morningstar SunSaver MPPT charge controllers and SureSine inverter.
Design and Software
The following shows how to use an analog to digital converter to measure voltages and transmit the data to a computer's serial port.
Basic design revised from beyondlogic.comSerial port reference information from beyondlogic.com
Datasheets for the ICs