USB ports are high speed ports with a serial data transmission and Hot Plug & Play installation of the connected peripherals. The connection of the devices is via a special USB cable. USB cable USB ports on the motherboard of a computer, USB hubs and USB peripherals. The cables are marked with the USB symbol. USB cables have two connectors and a 4-wire connection for a throughput of 12 Mbit / s and 1.5 Mbit / s for slow peripherals. With a USB cable needed to build a small fraction of the effort as for the construction of a parallel cable.
USB cable connector types with Type A and Type B connectors are there. The plugs of type A are for peripherals where the cable is plugged in permanently, such as hubs, keyboards and mice. Connector Type B are opposed to devices in which the cable is plugged in and out-such as with printers, scanners, modems, telephones and speakers. Physically, a USB connector is quite small and – unlike a typical serial or parallel cable – not attached with screws, but simply engages in one of the USB plug connection. The maximum cable length between two USB devices or a hub is 5 m using a pair cable twists. The cable length for slower peripherals by using non-twists-pair cable is 3 m. For the pin of a USB cable is: Pin 1 introduces the VCC signal, pin 2, the Data-Signal, Pin 3, the + Data and Signal Ground Pin 4 is the signal. The coat of the Shield signal. A variant of a USB cable may be that this is designed as a converter to older interfaces such as serial or parallel.