The GD photoelectric absolute value shaft angle coding sensor is composed of an encoder (product of P+F , Germany), a precision transmission gear train, and a flexible coupling. The encoder is an absolute value multi-turn digital, SSI synchronous serial interface output. In positioning control applications, absolute encoders eliminate the computational task of electronic receiving devices, eliminating the need for complex and expensive input devices. When the machine fails or is powered off, the current position value can be utilized as long as the machine returns to normal operation without returning to the position reference point. The sensor converts the actual mechanical parameter values ​​into electrical signals that can be processed by counters, tachometers, PLCs and computers. It is mainly used for the measurement and automatic control system of water, power, chemical and petroleum. It is especially suitable for the lifting measurement and control of hydropower plants, storage dams and ship locks.