AFAIK, the Bandit was limited to hardware handshake. You might try contacting Albrights's CNC support services in Bozeman, MT to acquire a cable and a prewired RS232connector. I do not have the pinout data on the Bandit, but the ones I saw had a round plug of some sort. I do not know if the DB25 was maybe for tape deck or what went on.
I'd make initial attempts at communication using an old PC with a real serial port on it. There's enough frustration to be had getting the communications going without throwing USB in the mix.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)