There are two stages, one which converts RS-232 to TTL, and the other converts TTL to USB. [André] removed the RS-232 chip and patched his own board (shown on the left) into its TTL lines.

It can be connected through UART (TTL, RS232), USB, as well as Ethernet, and is available as a PCB module and with Desktop housing. TWN4 MultiTech 2 is also compatible with over 60 of the most common ...