Remote I/O modules are industrial devices that enable distributed control by allowing input/output signals to be transmitted over long distances to a central controller. These modules are commonly used in automation systems to interface with sensors and actuators in harsh environments. Key features include rugged design for industrial use, support for various communication protocols (e.g., PROFIBUS, DeviceNet), and modular expansion capabilities. They help reduce wiring costs and improve system flexibility in applications like factory automation, process control, and machine monitoring.