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Test & Measurement World, July/August 2012

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Table 1. Comparisons of digital interface standards used in vision systems. FireWire-b Bandwidth Cable length Power + data over one cable Camera-control standard CPU usage 80 Mbyte/s 10 m Yes (45 W) IIDC Low will be able to connect USB 2.0 pe- ripherals to a USB 3.0-enabled com- puter, or connect USB 3.0 devices to a legacy computer. USB 3.0 Standard-A, Standard-B, and Micro-AB receptacles are also backward-compatible with USB 2.0. This relationship lets camera manufacturers focus on USB 3.0 tech- nology while still supporting USB 2.0 customers. Figure 1 shows a camera with USB 3.0 connector. USB 3.0 uses both sides of connector. USB 2.0 needs the left side only. One of the most compelling features of the USB 3.0 interface for machine- vision cameras is its high bandwidth. Because USB 3.0 provides an effective bulk-transfer rate of approximately 400 Mbyte/s, which is 10 times faster than USB 2.0 and five times that of IEEE 1394b, camera manufacturers can build USB 3.0-based cameras that in- corporate the fastest image sensors in low-cost packages. Previously, these sensors were limited to specialized high-speed cameras that offered on- board storage or that used complex in- terfaces to connect with expensive frame-grabber technology. To demonstrate the capabilities that USB 3.0 offers to vision applications, we performed a streaming test with two of our Flea3 cameras (a 1920x1080 camera at 60 fps and a 1280x1024 cam- era at 125 fps) connected to a single PCIe card. The two cameras success- fully generated a total of more than 280 Mbyte/s of image data. In the past, camera vendors often used onboard solid-state or compact- flash storage and limited the user to burst capture behavior constrained by the capacity of the storage medium. USB 3.0 now lets camera vendors sup- 100 m Yes with Power over Ethernet (15 W) GigE Vision Medium Gigabit Ethernet USB 2.0 100 Mbyte/s USB 3.0 40 Mbyte/s 5 m Yes (2.5 W) N/A High port image capture at high frame rates on a continuous basis, making it possi- ble to use these cameras in applications that require 24/7 operation. USB3 Vision promises plug-and-play To aid developers of machine-vision systems that use the USB 3.0 interface, the AIA and providers of machine-vi- sion cameras, software, and peripherals high-speed video and related control data. USB3 Vision will provide a framework for transmitting are developing the USB3 Vision stan- dard to permit interoperability of cam- eras, accessories, and software from dif- ferent manufacturers (Ref. 1). USB3 Vision is scheduled for release later this year, and components that comply with the standard will offer plug-and-play compatibility and will let developers interchange components with little or minimal effect on an overall system. The establishment of USB3 Vision en- sures greater compatibility between cameras and host imaging libraries, a benefit that wasn't available to USB 2.0. Like the popular GigE Vision stan- dard, which is also maintained by the AIA, USB3 Vision will provide a frame- work for transmitting high-speed video 400 Mbyte/s 5 m Yes (4.5 to 7.5 W) USB3 Vision (in progress) Low CAMERA LINK 680 Mbyte/s (8-tap) 10 m Yes with Power over Camera Link (4 W) Camera Link Medium and related control data. Also like GigE Vision, USB3 Vision will make use of the GenICam programming interface (developed by the European Machine Vision Association) to capture camera attribute behavior. This will minimize the need to modify the host software to support a new camera model. Developers who want to employ USB 3.0 should have no trouble find- ing affordable products for their sys- tems. Peripheral devices for USB 3.0 are becoming readily available on the market, and chipsets used to enable the technology are priced very aggressively due to the high-volume market of hard-drive storage. USB 3.0 is also currently supported by the majority of new laptop comput- ers. By 2015, all PCs are expected to support it. In terms of operating sys- tems, Windows 8 will provide native support, Intel has just announced its new 7-series chipset with native sup- port, and the Linux community is ac- tively developing a kernel driver to support USB 3.0 on Ubuntu and other Linux operating systems. T&MW Reference GigE Vision—True Plug and Play Connectivity, AIA, Ann Arbor, MI. www.visiononline.org/vision-standards- details.cfm. Paul Kozik is the product manager at Point Grey, one of the founding members of the USB3 Vision committee. He has worked for a number of imaging compa- nies in a variety of roles including applica- tions engineering, sales, and technical support before transitioning to product management. Kozik manages all imaging products from initial concept to complete life cycle. He holds a bachelor of engi- neering science (BESc) degree from the University of Western Ontario. Test & Measurement World | JULY/AUGUST 2012 | www.tmworld.com –29–

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