I'm having a similar problem on a BeagleBone Black (Rev C) running a minimal version of Debian Jessie. When I plug in my Sweep (via the Serial to USB adapter) to the BBB's USB port, nothing happens. The motor doesn't spin and the device is not listed under USB devices:
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
@JeroenAka , does it show up and/or spin in your case?
The same Sweep and adapter do work on my Macbook. And other USB devices (such as a Wi-Fi adapter) do work on the same BBB. So I'm pretty sure the issue has to do with the Serial to USB adapter, although I'm open to other ideas. For example, could it be a power thing?
Regardless, could we get some more info on the adapter you are using please ? Datasheet, vendor and product IDs, etc. And where can we get Linux drivers for it? Thanks