BenQ 9H.F6GPK.NA4 Installation Handbook page 19

Term
Upstream
Downstream
Hub
Root hub
Speed (low-speed,
full-speed and high-
speed)
Active (self-
powered) device
Passive (bus-
powered) device
USB connectors and receptacles
USB connectors and receptacles are grouped into two types: Type-A and Type-B.
Type-A
Connect
or
Standard
Mini
Micro
Type-B
Connect
or
Standard
Mini
Micro
USB cable length
For each passive connection between a two USB devices, the maximum length for USB 3.0 is 3
meters, and the maximum length for USB 2.0 is 5 meters. To extend USB connection beyond
this length limit, an active extension cable has to be used to ensure stable signal transmission
and reliable power supply.
The direction of data transmission from a USB function to a host or hub.
The direction of data transmission from a USB host or hub to a function.
A USB device that provides upstream connection (port) to a host and
downstream connections (ports) to multiple functions.
A USB host that also performs the functions of a hub.
Three different speeds are currently defined in the USB 2.0 specification:
• Low-speed: data transmission at 1.5Mbps
• Full-speed: data transmission at 12Mbps
• High-speed: data transmission at 480Mbps
The actual transmission speed is determined by the device with the
lower (or lowest) speed. For example, if a low-speed (1.5Mbps) USB
peripheral is connected to a high-speed (480Mbps) USB host, the
maximum transmission speed between these devices will be 1.5Mbps,
not 480Mbps.
A USB device that has it own power supply and can operate without the
power supplied by the USB host.
A USB device that does not have its own power supply and solely relies
on the power supplied by the USB host.
• Type-A receptacles are used as outputs from host systems
Recepta
and hubs.
cle
• Type-A plugs are always oriented towards the host system
and mate with Type-A receptacles.
• Type-B receptacles are used as inputs to hubs or devices.
Recepta
• Type-B plugs are always oriented towards a USB hub or
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device and mate with Type-B receptacles.
Description/explanation
Display installation guide 19