I posted a couple of days ago about determining that the USB cable-length limit is real, and needing to get a USB-CAT5-USB converter. I found a couple for only $8 (and free shipping) from “bargain cable” sold through Amazon. I ordered one of each, and they came today (order on Sunday, delivered on Tuesday is pretty good turnaround!).
Although the two parts I ordered had different prices:
HDE USB over Cat5/5e/6 Extension Cable RJ45 Adapter Set Sold by: bargain cable $8.60 each
USB over Cat5/5e/6 Extension Cable RJ45 Adapter Set Sold by: bargain cable $7.99 each
they were identical. The prices seem to be different today also, but within a few cents.
There is one minor problem: there is not a USB type-B connector on the slave end, but a USB female type-A. This is easily fixed (just plug in a standard USB A-to-B cable), but it does indicate sloppy engineering.
I tried hooking one set up with a 50′ CAT-5 patch cable (under $5 from Parts Express) that we are likely to use as part of the ROVtether. I had no trouble downloading Arduino programs or getting data back at 115200 baud—even powering the Arduino over the cable worked fine. So that seems to be one big problem solved very cheaply! I love it when off-the-shelf cheap parts do exactly what I need.