Design and application of intelligent supplemental light controller for pitaya based on PLC technology

【Objective】 Different plants have different requirements for light intensity and light quality. The goal was to achieve intelligent light supplementation for plants through real-time illumination from LED lights.【Method】 Aiming at the need for sufficient supplementary light for the growth and development of pitaya (Hylocereus undatus) and regulation of fruit stage, an intelligent regulator specially for light supplementation of pitaya was designed using a new generation of the programmable logic controller (PLC) technology and yellow LED lights with wavelengths of 570？590 nm, and the corresponding data transmission protocol was designed. The hardware selection, circuit design and software design were performed, and control strategy and remote communication protocol were establised. Finally, an actual deployment and application experiment was carried out in a 10666 m2 pitaya farm in Xinxing County of Guangdong Province. 【Result】 The regulator could achieve stable and long-term light supplementation for pitaya through manual, automatic and remote management, and data transmission was stable and reliable. The response time of the regulator was within 3 s, and light supplementation duration was 4 h. After using the regulator to supplement the light, the fruit ripening stage was advanced by 2？4 d, some pitaya trees bore 2？3 more fruits per tree, the output of pitaya fruit increased by 16.7%.【Conclusion】 The device realizes the intelligent supplementary lighting of pitaya. It has obvious economic and social benefits and has a good popularization prospect.