The error of data transmission appears when the flowing is overlow in the long distance communication.To solve this problem

a relay and measurement circuit of sensors is proposed used in long distance communication.The relay circuit works according to photoelectric isolation technology and current loop method.Current loop interface can work in 5 mA current

its communication distance is more than 500m or even further.The circuit is applied in environmental monitoring system of multi-sensor and data information fusion algorithm of fuzzy comprehensive evaluation is used to test data fusion.The experimental results show that the proposed relay detecting circuit is reliable

stable

and well realizes data transmission in long distance.