Cannot find serial device
You can open System Report and check under USB to see if your USB device was found and initialized.

In terms of device files, you'll want to search for tty* and cu* - do not include the dot.

An easy way to spot the correct device is to run first:

find /dev &gt; list1


then plug in the serial-USB adapter, and run:

find /dev &gt; list2


and then finally:

diff list1 list


then the name of the new device for the serial-USB adapter should be shown.