A protocol used in process industries that allows digital communication with instruments over the same wires as analog signals. Many analog field instruments (like pressure transmitters) use a 4-20 mA signal to indicate value, but with HART, they can also superimpose a digital signal on top of that current loop. This lets operators or control systems talk to the device, reading diagnostics, setting ranges, etc., without extra wiring. Think of HART as giving your “dumb” analog sensor a way to speak up and say more than just its measurement, all over the existing cable.
