USB - Hubs, Adapters, Firewire

USB - Hubs, Adapters, Firewire

Data Connect Enterprise offers a full range of USB - Hubs, Adapters, Firewire
As well as USB Peripheral devices

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Universal Serial Bus (USB) provides a serial bus standard for connecting devices, usually to a computer, but it also is in use on other devices such as set-top boxes, game consoles and PDAs.

A USB system has an asymmetric design, consisting of a host controller and multiple devices connected in a tree-like fashion using special hub devices. There is a limit of 5 levels of branching hubs per controller. Up to 127 devices may be connected to a single host controller, but the count must include the hub devices as well. A modern computer likely has several host controllers so the total useful number of connected devices is beyond what could reasonably be connected to a single controller. There is no need for a terminator on any USB bus.

The design of USB aimed to remove the need for adding separate expansion cards into the computer's ISA or PCI bus, and improve plug-and-play capabilities by allowing devices to be hot swapped or added to the system without rebooting the computer. When the new device first plugs in, the host enumerates it and loads the device driver necessary to run it.

USB can connect peripherals such as mice, keyboards, gamepads and joysticks, scanners, digital cameras, printers, hard disks, and networking components. For multimedia devices such as scanners and digital cameras, USB has become the standard connection method. For printers, USB has also grown in popularity and started displacing parallel ports because USB makes it simple to add more than one printer to a computer. As of 2004 there were about 1 billion USB devices in the world. As of 2005, the only large classes of peripherals that cannot use USB (because they need a higher data rate than USB can provide) are displays and monitors, and high-quality digital video components.

USB 1.1: Released in 1998

USB 2.0: Released in 2000. The major feature of this standard was the addition of high-speed mode. This is the current revision.

USB 2.0: Revised later in 2000. Added three speed distinction to this standard, allowing all devices to be USB 2.0 compliant even if they were previously considered only 1.1 or 1.0 compliant. The makes the backwards compatibility explicit but more difficult to determine a device's throughput without seeing the symbol. As an example, a computer's port could be incapable of USB 2.0's hi-speed fast transfer rates, but still claim USB 2.0 compliance (since it supports some of USB 2.0).

A Low Speed rate of 1.5 Mbit/s (183 KiB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice and joysticks.
A Full Speed rate of 12 Mbit/s (1.4 MiB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices. All USB Hubs support Full Speed.
A Hi-Speed rate of 480 Mbit/s (57 MiB/s).
Not all USB 2.0 devices are Hi-Speed. A USB device should specify the speed it will use by correct labeling on the box it came in or sometimes on the device itself. The USB-IF certifies devices and provides licenses to use special marketing logos for either "Basic-Speed" (low and full) or High-Speed after passing a compliancy test and paying a licensing fee.

Hi-Speed devices should fall back to the slower data rate of Full Speed when plugged into a Full Speed hub. Hi-Speed hubs have a special function called the Transaction Translator that segregates Full Speed and Low Speed bus traffic from Hi-Speed traffic. The Transaction Translator in a Hi-Speed hub (or possibly each port depending on the electrical design) will function as a completely separate Full Speed bus to Full Speed and Low Speed devices attached to it. This segregation is for bandwidth only; bus rules about power and hub depth still apply.

Patton 2192/USB USB V.92/56-kbps Dial-up Modem
Contract Buying and Volume Discounts available !!

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