While the Arduino family of boards connect to your computer using a USB virtual serial port, the ATmega ones have an actual serial connection on-board.

Although a “CommsLink” module providing an RS-232 port was available back in the day, it’s become hard to find, inspiring [James] to design a completely new module based on an Arduino Nano.

With Omega Engineering’s Model WRS232-USB universal wireless RS-232-to-USB transceiver, you can make any RS-232 device wireless. Simply connect the wireless transmitter module to the device’s RS-232 ...

Claimed as easy to use, the E5805A USB-to-RS232 interface can connect up to four RS232 test instruments to the USB port on a personal computer at baud rates up to 230 Kb/s per serial port.

The WRS232-USB, including one wireless transmitter module, one wireless receiver module, RS-232 cable with RJ12 to DB9 connector, DB9 male/male connector, USB cable, CD, and instruction manual, costs ...