y and signal loading, and the two lines do not distinguish polarity.Wired meter reading can be divided into pulse (active), camera (passive), resistive (passive) and optoelectronic (passive) according to the different ways of realization. from the view of the technical reliability, development direction and market share, optoelectronic water meter is the mainstream way, whatever wired or wireless applied.The meaning of direct reading meter is that at ordinary times no power supply, when meter re