You're on the right track though, KeithSloan.
There are a number of cables similar to this, and there are bound to be a few that use 5v logic instead of 3.3v.
For instance, a few years back when the "Hacking Roomba" book and community were new, there was a rush on a Verizon cable that simply needed to be spliced with the right connector. The trouble these days is mostly finding a cable with an onboard USB serial controller. As so many phones are beginning to have USB on board (even if the connector isn't US

most cables are simply pipes.