[Engineering Feature]
The USB 3.0 Speed Bump
Terry Costlow
ED Online ID #21020
April 23, 2009
Copyright © 2006 Penton Media, Inc., All rights reserved. Printing of this document is for personal use only.
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The latest version of USB, completed last year, increases bandwidth
up to 5 Gbits/s, moving 25 Gbytes in only 70 seconds. While most
industrial applications won’t need that much speed for I/O applications,
observers feel that USB 3.0 will eventually play a role in applications
that move lots of data.
Though the first CPUs supporting the standard won’t move into high
volume until later this year, industrial designers are already speculating
how engineers may use it in manufacturing. At those speeds, the
standard—also called SuperSpeed USB—is expected to see use in
applications like vision and high-performance data acquisition.
Makers of data-acquisition systems are looking at the standard for
demanding applications. And, suppliers like Tektronix and LeCroy are
rolling out test equipment that will help designers finalize their USB
3.0 designs.
There are other industrial applications as well. “Areas such as wireless
communication, audio, and fast read/write applications such as
recognition will all be pushing the 3.0 technology,” says Susan Wooley,
president of Micro/Sys. However, she noted that embedded users are
rarely early adopters of consumer standards, so it will be quite some
time before SuperSpeed makes its way into industrial apps.
In machine vision, there’s a chance that USB 3.0 could compete
with 1394. It doesn’t offer isochronous capabilities, but it has enough
bandwidth to become a link for cameras.
“USB 3.0’s speed could make it a bigger player,” says Jeff Fryman,
director of standards development for the Automated Imaging Association
(AIA).
However, some observers note that USB cables can’t stretch more
than three meters. That will be a roadblock for applications including
vision, where cameras and other devices are often more than 10 feet
from controllers.
But many industrial applications don’t need long cables. For them,
USB 3.0 offers benefits beyond speed. It reduces power consumption
by eliminating the polled architecture used until now. SuperSpeed
nodes also tell the host when they have traffic, eliminating the power
consumption often associated with frequent polling.
Adaptive equalization should help users set up systems. In addition,
the amount of power available for devices is nearly doubled. USB
3.0 provides a maximum draw of 900 mA, up from 500 mA for USB
2.0, sometimes called HighSpeed USB.
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