中文摘要：

提出基于PLC的温湿度、光照度信号检测系统的设计方法，为软测量模型提供必需的输入因子。同时，由于农田环境较为复杂，采集的信号较弱，因此设计了一种信号放大电路来实现信号的放大功能。

英文摘要：

This article proposed a design method of detecting temperature（T）, humidity（H） and illuminance（I） signal automatically based on the PLC in order to provide the necessary inputting factors for soft survey model. At the same time, one kind of signal enlargement electric circuit is also designed to realize the signal enlargement function for the complex farmland environment and the weak gathering signals.