I've recently run into a scenario where I need to pick between a singled ended current input (4-20mA) input device and a differential current input device. Single Ended and Differential. I've never run into (or so I believe) the case where I had a differential current output sensor, thus I've never looked into an I/O card that accepts a differential input current signal.
So my question - when would I know if I needed to use a differential input card? It seems like most 4-20mA transmitter circuits operate in a 2 wire interface. Is the two wire interface always considered to be single ended? Thus the only time I would ever need to think about using a differential input card for a current output, is if there was a non-two-wire interface?
I guess I'm more familiar with the concept of single-ended and differential in the context of voltage I/O, not current I/O.