Does anyone know of an adapter that converts USB to Serial RS-232 that works with Mac OS 10.10x?

Does anyone know of an adapter that converts USB to Serial RS-232 that works with Mac OS 10.10x? My iogear adapter I just bought only supports up to Mac 10.9x and I cannot connect to an external machine using an RS-232 Connection using this adapter (or at least I haven't been able to yet). I can't even see the device in the terminal using the ls /dev/tty.* command after installing the driver and restarting the Mac Mini. Are there other adapters or methods that I should try? Or has anyone been successful in using/controlling an RS-232 device with Mac Os 10.10x.3?