Rope displacement sensor, also known as rope sensor, rope electronic ruler and rope encoder, is a kind of sensor used to measure linear position. It combines the advantages of angle sensor and linear displacement sensor, and has the characteristics of small installation size, compact structure, large measuring stroke and high precision, ranging from hundreds of millimeters to tens of meters. Measuring the opening of the gate: the pull-rope/linear displacement sensor can directly measure the displacement of the gate leaf or arm, thus indirectly reflecting the opening of the gate.