I am trying to communicate from Arduino Uno (TTL serial) to a Tandberg video codec (C20) via RS-232 serial (12v). Using a Parallax USB232 interface I can TX/RX RS-232 serial commands from my Mac to video codec. I can also TX/RX serial commands from Mac to Arduino. Now it's time to get the Arduino Uno talking serial straight to the video codec.
It appears that the Parallax USB232 interface is getting power from the Mac's USB port. Can I simply power the USB232 interface via its USB Pin 1 with 5v from the Uno? The Arduino Uno will be powered through the barrel jack. Thanks.