A Universal Serial Bus Cable, normally referred to as a USB cable, is primarily used to connect a USB device to a host. Common hosts include computers and video game consoles. While there are multiple USB standards, cables that are fully compliant with USB 1.1 specifications will work with USB 2.0 technology and vice versa. USB cables can be identified by the USB-trident on top of the plug overmolds of type “A” and “B” connectors.
????? A USB Connector??can have numerous types of plug ends, the style of which is called a connector. Connector types include Standard-A, Standard-B, Mini-B, Micro-A, Micro-B, and Micro-AB. These plugs go into corresponding receptacles built into hosts and devices. Standard-A receptacles are the type commonly referred to as USB ports on computers; Standard-B receptacles are usually found on large peripheral devices such as printers and scanners; Mini- and Micro- receptacles are usually on small devices like digital cameras and cellular phones; Mini-AB receptacle are, according to the standard, only on “USB On-The-Go” devices. Most USB cables that connect a device to a computer will have a Standard-A plug on one end and another type of plug on the other.

????? Beyond connector types, compliant USB cables are not proprietary. A standard USB cable can connect a device to a Macintosh or a Windows-based PC, for example. The software within the device, however, may not work with the host. In addition, some companies create cables that appear similar to USB cables but are not compliant with USB standards - such connectors should not have the USB trident logo on them.

????? A standard USB cable contains multiple wires. One wire contains a path for a five volt (5V±5%) power supply; two are twisted-pair data wires; and one is a ground. As mentioned previously, companies have been known to create non-compliant USB-style cables to work exclusively with their products.

????? A USB cable under 2.0 specs can only be five meters (roughly 16.4 feet) long. This limit was established due to a cable delay spec of 26 nanoseconds, which allows for reflections to settle at the transmitter before the next bit is sent. USB hosts must have their commands answered within an allowed time frame or they will consider the commands lost - cables significantly longer than five meters would result in too much of a delay.

????? There are many solutions for connecting USB devices beyond the 5 meter cable limit. These solutions include using USB extender cables, which are self-powered hubs with a fixed 10 meter cable and a one-port bus powered hub in the middle; using up to five USB hubs in a chain; and building a USB bridge that acts as a USB device on one side and has a USB host controller at the other end. The USB Implementers Forum, Inc., recommends using a long-haul signaling protocol like Ethernet or RS-485 in the middle if this method is used.