- How far away from a PC can I put a USB device?
With the maximum of 5 hubs connected with 5m cables and a 5m cable going to your full speed device, this will give you 30m of cable (see section 7.1.19 for details). With a low speed device, you will be able to get a range up to 27m, depending on how long the device's cable is. With straightforward cable route, you will probably be able to reach out 25m or so from the PC.
- I need to put a USB device X distance from my PC. What do I do?
If X is less than 25m or so (see previous question), buy a bunch of hubs and connect them serially with 5m cables. If you need to go farther than that, put another PC, or maybe a laptop, out where you need the device to be and network it with the first PC using something that's intended to be a long-range connection, such as Ethernet or RS-485. If you need to use nothing but USB, consider using USB based Ethernet adapters to hook the PCs together.
- How can I connect two PCs to each other with USB?
You need a specialized USB peripheral known as a USB bridge (sometimes called a USB to USB adapter) to do this. Without a USB bridge, connecting a USB port of a PC directly to another PC's USB port can damage the computers.
- What if I want to network a whole bunch of PCs together with USB?
If you need to connect just a few machines, USB bridges and a hub or two will work. USB was not designed to be a LAN, however, and there are certain safety hazards associated with trying to use USB with large numbers of PCs. There's also a large performance penalty compared to a real LAN. If you need a LAN, use a technology intended to be used as a LAN, such as Ethernet.