I am working with a multiwii right now and it uses a "FT232R USB UART". When I had El capitan i could find the devices serial in my ports (i remember i had problems with it too though but i solved it after a while) but when i upgraded to mac os sierra i cannot find the serial in my "ports" anymore.
I followed this guide where i tried to install ftdi-drivers again, unload the Apple supplied Drivers. (which i might need to enable again? not sure how to do it) etc but the problems still remains.
I also saw a post about using Apples own FTDI driver but I am not quite sure on how to execute it.
Any tips & help is very appreciated!!!