https://books.google.com.tw/books?id=X5lCAwAAQBAJ&pg=PT414&l...
Edit: Maybe it is no issue with USB hub, but not work with too many usb controller (USB port to MB directly)?
It might be true if you have old devices, though. If you have USB 1.0/1.1 full speed HID devices you can overcommit the available bandwidth for a human interface device. HID devices generally require that they be serviced every 1ms with a 64 byte packet. You might overrun that if you put enough old devices together on an old hub. It's quite unlikely for USB 2.0+ with anything High Speed.
The only issue with new devices is that USB 3.0+ requires twice the endpoints of USB 2.0. The problem is that the Intel controller chips allocate the same amount of memory for USB 3.0 as they do USB 2.0. So if you have a system with a lot of devices (96+), you can hit the memory limit of the controller.
We hit that limit with a 192 device system. It took a while to figure out what the heck was wrong.
[0] https://www.yoctopuce.com/EN/article/how-many-usb-devices-ca...
That's ok. People have different needs. For me it is mostly many hard drives, exercise equipment, multiple cameras, some stuff I am testing and lots of smaller things.
Indeed, a buddy of mine has at least 6 or so going at once for his 3D printing business, and we're considering a similar sort of strategy (w/ e.g. some box running Slic3r and Octoprint) so he ain't constantly running USB sticks back and forth.
That's... pretty much exactly the plan, yes. The printers we're using all (to my knowledge) run some version of Marlin w/ SD support, so we'd be doing this via the M28/M29 GCode commands over that same USB interface.
It ain't clear that OctoPrint supports this directly, but as long as it's able to shove the exact GCode we tell it to shove we should be able to make that happen. Since Marlin's supposed to wait until it gets an M29 command before it starts printing, it seems to me like low throughput would therefore be a non-issue (aside from, you know, the amount of time it'd take to push that data across, but that'd really only be an issue for the first time we're printing a new file).
https://dortania.github.io/OpenCore-Post-Install/usb/#macos-...