The D-Link DU-CS Serial On USB Port is a device that allows you to connect a serial (RS-232) device to your computer via a USB port. It's commonly used for connecting older devices, such as industrial equipment, networking hardware, and serial-based peripherals, to modern systems that lack a traditional serial port (COM port). The device essentially acts as a USB-to-Serial adapter, allowing your computer to communicate with serial devices.

The Windows driver for the D-Link DU-CS adapter allows the operating system to recognize the adapter and establish communication between your computer and the connected serial device.