Install the Driver:
Connect the Printer:
Verify Installation:
First, a clarification. The Epson UB-U03II isn’t a printer itself. It’s a USB-to-Serial (RS-232) converter box (sometimes called an interface unit) used with Epson’s TM series printers (like the TM-T88 or TM-U220). It allows a modern Windows 10 PC without serial ports to communicate with legacy serial printers via USB.
Without the correct driver, Windows 10 sees the device as an “unknown USB device” or fails to create a virtual COM port.
Do not download drivers from third-party "driver download" websites. They often contain malware or outdated files. Always use the official Epson support portal.