SMART Technologies 800 User Manual

Extending USB connections

In USB topology, the hub is the only device that you can use to link USB devices. The distance

between hosts and devices, therefore, is limited by the maximum USB cable length allowed between

devices and the maximum number of hubs allowed in a path.

Basic USB connection

In the following diagram, you can see that if all USB hub connections use 16' (5 m) cables, the

maximum distance between a host’s root hub and a function is 6 × 16' (5 m) = 96' (30 m).

Root

Hub

Function

Host

Host (Tier 1 ) Tier 2 Tier 3 Tier 4 Tier 5 Tier 6 Tier 7

16 ' (5 m ) + 16 ' (5 m ) + 16 ' (5 m ) + 16 ' (5 m ) + 16 ' (5 m ) + 16 ' (5 m ) = 96 ' (30 m )

Compound device connection

In this diagram, you can see that connecting a compound device limits the maximum distance to

5 × 16' (5 m) = 80' (25 m).

Compound device

Root

Hub

Function

Host

Host (Tier 1 ) Tier 2 Tier 3 Tier 4 Tier 5 Tier 6 Tier 7

16 ' (5 m ) + 16 ' (5 m ) + 16 ' (5 m ) + 16 ' (5 m ) + 16 ' (5 m ) = 80 ' (25 m )

N O T E

SMART Board 800 series interactive whiteboard systems are compound devices.

A P P E N D I X A

USB 2.0 specification primer