The main advantage of a two-wire loop is that it minimizes the number of wires needed to run both power and signal. The use of a current loop to send the signal also has the advantages of reduced sensitivity to electrical noise and to loading effects.
The electrical noise is reduced because the two wires are run as a twisted pair, ensuring that each of the two wires receives the same vector of energy from noise sources, such as electro- magnetic ï¬elds due to a changing current in a nearby conductor or electric motor. Since the receiving electronics connected to the transmitter is designed to ignore common-mode signals, the resulting common-mode electrical noise is ignored.