Devices that operate with a 4-20mA current output do this in the form of a fault current (NAMUR 43) or HART data output, while smart transmitters send indications over their digital network.

A simple temperature sensor using a two-wire transmitter for PRTDs combined with the still-popular 4 to 20 mA analog current ...

With an eye on factory automation, Maxim has released a reference design for a precision 4-20mA temperature transmitter with added data capability. The whole thing, branded Novato, is loop-powered, ...