What are the common types of IO extension modules?

IO expansion module is a hardware device used to expand device input/output interfaces. According to different application scenarios and requirements, IO expansion modules can be divided into multiple types. Here are some common types of IO expansion modules:

1. Digital Input Output Module: A module used to control and monitor the input and output of digital signals. Common digital input/output modules include modules based on switches, relays, and transistors.
2. Analog Input Output Module: A module used to process and monitor analog signal input and output. Common analog input/output modules include modules based on resistors, transistors, and optocouplers.
3. Communication Interface Module: A module used to implement communication between devices. Common communication interface modules include modules based on RS232, RS485, Ethernet, and CAN interfaces.
4. Special Function Module: A module used to implement specific functions. For example, PWM (Pulse Width Modulation) modules are used to control the speed and direction of motors, while counting modules are used to implement counting functions.

The price of IO expansion modules may vary due to differences in brand, model, and functionality.