Editing USB (section)

== Cabling <span class="anchor" id="CABLING"></span>==
{{Main|USB hardware#Cabling}}
[[File:Cables in Hong Kong.JPG|thumb|A variety of USB cables for sale in [[Hong Kong]]]]

The USB&nbsp;1.1 standard specifies that a standard cable can have a maximum length of {{convert|5|m|ftin|sp=us}} with devices operating at full speed (12&nbsp;Mbit/s), and a maximum length of {{convert|3|m|ftin|sp=us}} with devices operating at low speed (1.5&nbsp;Mbit/s).<ref>{{cite web |url=http://www.cablesplususa.com/pdf/USB_Cable_Length_Limitations.pdf |title=USB Cable Length Limitations |website=CablesPlusUSA.com |date=3 November 2010 |access-date=2 February 2014 |archive-url=https://web.archive.org/web/20141011015850/http://www.cablesplususa.com/pdf/USB_Cable_Length_Limitations.pdf |archive-date=11 October 2014}}</ref><ref>{{cite web |url=https://www.techwalla.com/articles/what-is-the-maximum-length-of-a-usb-cable |title=What Is the Maximum Length of a USB Cable? |website=Techwalla.com |access-date=18 November 2017 |url-status=live |archive-url=https://web.archive.org/web/20171201043247/https://www.techwalla.com/articles/what-is-the-maximum-length-of-a-usb-cable |archive-date=1 December 2017}}</ref><ref name="faq"/>

USB&nbsp;2.0 provides for a maximum cable length of {{convert|5|m|ftin|sp=us}} for devices running at high speed (480&nbsp;Mbit/s).<ref name="faq">{{Cite web | url = http://www.usb.org/developers/usbfaq/#cab1 | title = Cables and Long-Haul Solutions | work = USB 2.0 Frequently Asked Questions | publisher = USB Implementers Forum | access-date = 28 April 2019 | url-status=dead | archive-url = https://web.archive.org/web/20110118225750/http://www.usb.org/developers/usbfaq/#cab1 | archive-date = 18 January 2011}}</ref>

The USB&nbsp;3.0 standard does not directly specify a maximum cable length, requiring only that all cables meet an electrical specification: for copper cabling with [[AWG]]&nbsp;26 wires the maximum practical length is {{convert|3|m|ftin|sp=us}}.<ref>{{cite web |title=USB 3.0 Developers FAQ |url=http://janaxelson.com/usb3faq.htm#ca_maximum |access-date=20 October 2016 |last=Axelson |first=Jan |url-status=live |archive-url=https://web.archive.org/web/20161220073858/http://www.janaxelson.com/usb3faq.htm#ca_maximum |archive-date=20 December 2016 }}</ref>

=== USB bridge cables ===
USB bridge cables, or data transfer cables can be found within the market, offering direct PC to PC connections. A bridge cable is a special cable with a chip and active electronics in the middle of the cable. The chip in the middle of the cable acts as a peripheral to both computers and allows for peer-to-peer communication between the computers. The USB bridge cables are used to transfer files between two computers via their USB ports.

Popularized by Microsoft as [[Windows Easy Transfer]], the Microsoft utility used a special USB bridge cable to transfer personal files and settings from a computer running an earlier version of Windows to a computer running a newer version. In the context of the use of ''Windows Easy Transfer'' software, the bridge cable can sometimes be referenced as ''Easy Transfer cable''.

Many USB bridge / data transfer cables are still USB 2.0, but there are also a number of USB 3.0 transfer cables. Despite USB 3.0 being 10 times faster than USB 2.0, USB 3.0 transfer cables are only 2 to 3 times faster given their design.{{clarify|reason="given their design" suggests there are reasons for this, what are they?|date=October 2022}}

The USB 3.0 specification introduced an A-to-A cross-over cable without power for connecting two PCs. These are not meant for data transfer but are aimed at diagnostic uses.

==== Dual-role USB connections ====
USB bridge cables have become less important with USB dual-role-device capabilities introduced with the USB 3.1 specification. Under the most recent specifications, USB supports most scenarios connecting systems directly with a Type-C cable. For the capability to work, however, connected systems must support role-switching. Dual-role capabilities requires there be ''two'' controllers within the system, as well as a ''role controller''. While this can be expected in a mobile platform such as a tablet or a phone, desktop PCs and laptops often will not support dual roles.<ref>{{cite web |url=https://superuser.com/questions/1080002/usb-3-1-type-c-host-to-host |title=USB 3.1 - Type-C Host to Host |website=superuser.com |access-date=21 July 2021 |archive-date=14 October 2021 |archive-url=https://web.archive.org/web/20211014022330/https://superuser.com/questions/1080002/usb-3-1-type-c-host-to-host |url-status=live }}</ref>