text: No serial com port over USB on OSX
  I have the same problem with both the WiPy and LoPy. I am unable to get a serial connection over usb/extension board. I'm using OSX 10.12.1.
  - I can connect over telnet and ftp
  - all jumpers are in place
  - the usb cable has data lines
  - I can connect to the original pboard over usb
  - No com port shows when I type ls /dev/cu.* (other than the built-in bluetooth)
  - I'm running the latest firmware on the LoPy
  I'm guessing that this is a driver issue, but I've had no luck with those that have been posted on the forums in the past. Please help!
  so on my iMac, running El Capitan, it is /dev/tty.usb. That is the same as I found it in various post on the Internet. I usually enter "screen /dev/tty.u<tab> 115200" on the commandline.
  Have you tried rebooting the Mac? I had the same problem and the reboot helped.
  Thanks for the info. Are you sure you have the FTDI drivers installed? If you can connect over telnet to the REPL, the driver is the only issue I can think of, besides a broken expansion board. Let me know if (re)installing these drivers help with your problem, otherwise we'll have to look in to this some more.