HP 2TB User Manual download pdf (Page 27)

The transfer speed capabilities of a device are often referred to by the USB specification revision

in which the transfer rate was defined. Therefore a USB 3.0 and a USB 2.0 Hub will support high,

full and low speed, but a USB 1.1 hub will only support full and low speed.

The USB specification was developed and is maintained by the USB organization. The USB

organization also conducts a certification program. The USB organization will issue the USB logo

to a device, which has passed a series of tests that verify the device has correctly implemented the

USB interface, as defined by the USB specification. There are many types of USB logos depending

on which features of the USB specification a device supports. A USB 2.0 logo-ed device correctly

supports high, full, and low speed data transfer.

Setting up a USB network

USB is very user friendly. The interface automatically assigns addresses to devices; you simply

need to connect a USB device to a USB port on a system using a USB cable. If you have many

USB devices or need to place a device away from your system, you may place up to a maximum

of five USB hubs between the device and host system and connect them with additional cables.

If you are using a high-speed (USB 3.0 or USB 2.0) device, make sure that the USB host at the

system and all the hubs between the device and host support high-speed (USB 3.0 or USB 2.0

2.0) transfer.

When using a bulk transfer device, such as an RDX Removable Disk Backup System, do not use

other USB devices that will place restrictions on the USB bandwidth available to the bulk transfer

device.

If several USB devices requiring large amounts of the USB network bandwidth are to operate

simultaneously, an additional host must be added to the system. Each device must then be placed

into the separate networks starting at the different hosts. An additional host is typically a new USB

HBA, which plugs into the host system's PCI slot, creating a new USB host that resides on the

network. (Note: if several USB adapters are placed into a system, demands on the bandwidth of

the system bus will constrain the USB devices' performance.)

Always use USB logo-ed components in your USB network. This is the best and easiest method to

ensure reliable operation.

USB cables

USB cables are available in a variety of lengths. The maximum cable length is 5 meters. If you

need to place a USB device further than 5 meters from the system, you must use a hub.

Do not use USB cable extenders or couples. These are not recognized or approved by the USB

organization. The USB specification does not allow their use and they are likely to reduce the

reliability of the USB network or cause it not to work completely.

Internal and external USB devices use the same USB cables.

Setting up a USB network 27

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HP 2TB User Manual Page 27