The old fashioned way would be a 4-20ma current loop. Other than power=20 consumption, I cannot think of a simpler way. On 12/2/2014 1:07 PM, Neil wrote: > I have not, but I did coincidentally spend the last 15 minutes looking > up termination resistors. Everything points to RS232 and RS485 though, > so I want to find a good intro to how to calculate the ideal termination > resistor value for my individual-conductors system. > > Cheers, > -Neil. --=20 John Ferrell W8CCW Julian NC 27283 It is better to walk alone, than with a crowd going the wrong direction. --Diane Grant --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .