LaCie Two Big eSATA & USB
User Manual
page
What Are The Ideal Applications For
Hi-Speed USB 2.0?
Digital cameras, CD/DVD drives, hard drives and
scanners will all benefit from the added bandwidth and
performance gains of the new implementation of the
USB standard. Hi-Speed USB 2.0 provides the neces-
sary fast data transfer rates that today’s devices require,
and combines the earlier specifications so older devices
that operated under the original USB standards will still
work with Hi-Speed USB 2.0.
Will USB Devices Run Faster When Connected To A
Hi-Speed USB 2.0 Bus?
Unfortunately, no. The Hi-Speed USB 2.0 specifica-
tion is specifically written to allow developers to design
higher speed peripherals that can take advantage of the
extra bandwidth. USB devices, though, will still operate
at 12Mb/s at full-speed and 1.5Mb/s at low-speed on a
Hi-Speed USB 2.0 bus. Even though USB devices won’t
run any faster, they can work alongside Hi-Speed USB
2.0 devices on the same bus. However, if you plug in a
Hi-Speed USB 2.0 device to a USB bus, the speed of
the Hi-Speed USB 2.0 device will decrease to 12Mb/s.
What Is A USB Hub?
Technically, you can connect up to 127 devices to a
single USB bus. For more than two devices, though, you
must make new connections using a peripheral called
a “hub.” A hub, which you hook up directly to a USB
connector on your computer, usually has 4 or 7 output
connections enabling you to connect the same number
of peripherals. One of the hub’s main functions is to re-
generate signals that lose strength as they are transmit-
ted via the USB cable. By connecting yet another hub to
a connector on the existing hub, you can then plug in a
new set of peripherals etc, up to a maximum of 127.
Some hubs have no power supply and others are
self-powered. When you choose a hub, opt for the self-
powered variety, as they have their own AC adapter.
The most powerful hubs provide 0.5A of power to each
port.
If you buy a hub, make sure that it supports per-port
switching. This function prevents the entire chain of pe-
ripherals from freezing up if one of them is not working
properly or is down.
Will Hi-Speed USB 2.0 Devices Work On USB Hubs
And Vice Versa?
You can use your Hi-Speed USB 2.0 devices with
USB hubs, but the peripherals will be limited to USB
performance levels.
There are Hi-Speed USB 2.0 hubs that are able to
communicate in three modes: high-speed (480Mb/s),
full-speed (12Mb/s), and low-speed (1.5Mb/s). Hi-
Speed USB 2.0 is backwards compatible, so you will
be able to connect USB devices to Hi-Speed USB 2.0
hubs; however, the USB devices will still maintain their
normal performance levels (i.e. 12 Mb/s).
In order to achieve the fast data transfer rates of Hi-
Speed USB 2.0, you must connect your Hi-Speed USB
2.0 device directly to a Hi-Speed USB 2.0 port on ei-
ther a computer or hub.
For more information about the USB interface,
please visit:
www.lacie.com/technologies
TeChNICAl NOTe:
Avoid using USB connec-
tors found on certain peripherals such as keyboards.
These are passive (or passthrough) longer cables may
cause the peripherals to malfunction due to excessive
reduction in electrical signal strength.
Tech Tips
