CHAPTER 2
2 - 21
COPYRIGHT
2000 CANON INC. CANOSCAN N650U/N656U/N1220U REV.0 JUNE 2000 PRINTED IN JAPAN (IMPRIME AU JAPON)
Figure 2-22
Host computer
Hub 1
Hub 2
Hub 3
Hub 4
Hub 5
Node
Node
Hub 6
Node
Node
Node
Node
Node
Node
Node
Layer 1
Layer 2
Layer 3
Layer 4
Layer 5
Layer 6
B. Outline of USB
The scanner is connected to the host computer via USB. USB (Universal Serial Bus) is the
next generation general-purpose input-output interface to connect the computer peripheral
devices.
1. Features of USB
1) Connects peripheral devices to a computer.
2) Connects up to 127 devices by a tree structure.
3) Connects by 12 Mbps of "full speed mode" or 1.5 Mbps of "low speed mode". This scanner is
conforming to "full speed mode".
4) Supports hot plug (connectable/disconnectable with the power ON).
5) The scanner power is supplied through USB.
2. Connection of USB Devices
USB devices are connected to a host computer by a tree structure consisting of device
called "node" and "hub" which is a group of "node" as shown in Figure 2-22. The tree
structure has the following conditions.
1) Able to connect up to 127 "node" and "hub" in total.
2) Limited up to 6 layers.
3) USB cable must be 5 meters or shorter.