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.

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.

Some of them are connected to native serial ports, and some have USB->RS232 adapters. I am communicating to them via the serial port interface and their /dev/ttyUSB* device nodes.

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.