On 28/01/11 14:15, Mark Rogers wrote:
Taking another sideways step, you can get a multimeter on eBay for about £30 that has a USB port, although no mention of drivers for Linux.
If you look at the Uni-T ones then there are perl and python scripts kicking around the net that will extract the data. However there is a problem.
All meters that meet a reasonable safety standard have an optical data connection which means they cannot be bus powered. My Uni-T running with the data connection enabled and the power save turned off manages a couple of weeks at best from high quality cells.
I think Brett's idea makes the most sense. Use a relay with a mains coil to pull a parallel port pin down (I'd suggest pins 12 and 13 are easiest to work with)
Load the pyParallel module http://pyserial.sourceforge.net/pyparallel.html
then use
getInPaperOut() or getInSelected() to read the status of pins 12 or 13 respectively
Shimples