A simple converter can be sourced online, but the only thing he could find locally that was even close was a USB to RS-232 converter. He used that component to craft his own USB to RS-485 bridge.

The Nucleus USB to RS232 adapter class driver has been designed to work with USB to RS232 converter hardware to solve the aforementioned problem for embedded hosts. Therefore, this class driver allows ...

FTDI is selling a USB-RS232 adapter as a replacement for DB-9 connectors. ... Now we get to keep our rs232 interface circuits and certainly there are their counter pairs inside these modules, ...