1、 Type of analog module (1) Analog input module The analog input module, also known as the A/D module, converts analog signals collected from various industrial field sensors into digital quantities that the CPU can recognize and receive. (2) Analog output module The analog output module, also known as the D/A module, simply converts the digital signal sent by the analog input module CPU into information such as voltage or current recognized and received by other external devices. (3) Digital quantity module The main function of the digital quantity module is to check the status of external switch inputs. Digital input and output signals are binary star signals, 1 or 0. 2、 Functions of analog quantity module 1. The main function of the analog input module is to collect analog signals. After collecting external pressure sensors, the analog signals collected by the pressure sensors are collected inside the module and processed accordingly. Here The sensor data includes analog values such as voltage, current thermal resistance, thermocouple, temperature, etc., and is then transmitted to the intelligent module of the computer through a bus. 2. The function of the analog output module is to convert the input digital signal through digital to analog conversion, and output controllable continuous current and signal. 3. Digital module: The digital module has two functions: input and output. If this method of integration is not used, more space can be saved. Otherwise, users need to buy two modules when using them. The digital module solves this problem by integrating input/output functions, where a module can input and output signals.