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Usb cables, Prohibited cable assemblies – Smart Technologies Smart Board 800 Series User Manual

Page 24

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USB cables

For full-speed and high-speed connections, USB 2.0 specifications allow two types of cable

assemblies:

l

a standard detachable cable that is terminated on one end with a Series-A plug, and terminated

on the opposite end with a Series-B plug

l

a captive cable that is terminated on one end with a Series-A plug, and has a vendor-specific

connection on the opposite end for the peripheral

l

a standard detachable cable that is terminated on one end with a Series-A plug, and terminated

on the opposite end with a Series-B plug

l

a captive cable that is terminated on one end with a Series-A plug, and has a vendor-specific

connection on the opposite end for the peripheral

I M P O R T A N T

Any other cable assemblies are prohibited.

Prohibited cable assemblies

USB 2.0 specifications prohibit specific cable assemblies. Prohibited cable assemblies may work in

some situations, but they cannot be guaranteed to work in all instances.

An example of a prohibited cable is the “extension cable.” This type of cable assembly has a Series-A

plug and a Series-A receptacle or a Series-B plug and a Series-B receptacle. This “passive” extension

cable allows you to connect multiple cable segments, possibly exceeding the maximum permissible

cable length.

Another example of a prohibited cable is one with both ends terminated in either Series-A plugs or

Series-B receptacles, allowing two upstream ports or two downstream devices to be connected

together.

A P P E N D I X

A

USB 2.0 specification primer

20