FireWire cameras tackle tough EMF environments
One benefits of the FireWire (1394) interface is its plug-and-play capability.
One benefits of the FireWire (1394) interface is its plug-and-play capability. Already, a number of companies offer such cameras, including Allied Vision Technologies (Stadtroda, Germany;www.alliedvisiontec.com), Basler (Ahrensberg, Germany; www.baslerweb.com), Cohu (San Diego, CA, USA; www.cohu-cameras.com), and Point Grey Research (Vancouver, BC, Canada; www.ptgrey.com).
With the advent of 1394b PHY devices from companies such as Texas Instruments (Dallas, TX, USA; www.ti.com), vendors including Point Grey and Prosilica (Burnaby, BC, Canada; www.prosilica.com) are enhancing their products, offering up to 3.2 Gbits/s and distances of 100 m on UTP-5 plastic optical fiber and 500 m on glass optical fiber. Because the 1394b standard is backward-compatible with the current 1394-1995 and 1394a standards, older 1394a-based cameras will work with a 1394b host adapter.
Networking FireWire-based cameras over optical fiber is now a matter of plug-and-play, thanks to products such as the Prosilica CV1280F camera. The camera can be networked over distances of up to 500 m .
At The Vision Show East (May 2004; Boston, MA, USA), Prosilica demonstrated the latest version of its CV640 and CV1280 cameras, showing how they could be used to transfer data over optical fiber and how they could be interfaced to existing 1394a peripherals. Marty Furse, Prosilica CEO, demonstrated both the company's CV1280F and the CV640 machine-vision cameras. Using CMOS imagers from FillFactory (Mechelen, Belgium; www.fillfactory.com) and Micron Technology (Boise, ID, USA; www.micron.com), both DCAM-compliant cameras feature FireWire interfaces.
In the design of the 1280 × 1024 CV1280F, however, Prosilica has chosen to integrate a 1394b PHY device with a 1394a LINK device to allow the camera to operate over a fiber interface. According to Furse, two methods can be used to interface the camera to a PC. For simple single-user applications, the company offers a $500 PCI-based add-in board that allows the fiber output of the camera to be directly interfaced to the host using a 1394b fiber connector. This allows 1280 × 1024-bit images to be transferred as fast as 29 frames/s to the host computer.
One of Prosilica's customers has an underwater stereo imaging application that illustrates the value of the CV1280F fiberoptic output. In this application, a sled carrying two Prosilica cameras is towed 400 m behind a boat on which the host computer is located. One of the cameras is a CV1280 1394a camera, which is daisy-chained to a CV1280F camera (the CV1280F has both a 1394a port and a 1394b-optical port to facilitate daisy-chaining). The fiber output of the CV1280F connects directly to the 1394b-optical PCI interface card in the host computer on the boat that is 400 m away. Images from both cameras are conveyed along the fiber interface of the CV1280F.
"In many machine-vision-system designs," says Furse, "several FireWire peripherals must be networked together. These may include 1394b and legacy 1394a devices." In such applications, the fiber output from the camera can be interfaced to such products as a Firenex 800 hub from Newnex Technology (Sunnyvale, CA, USA; www.newnex.com) as far as 500 m from the camera. To interface the camera to other peripherals, designers must be aware that the physical interface between 1394a and 1394b is different, and cables with a 1394a connector on one end and a 1394b connector on the other are needed to transfer data between FireWire devices.
At the show, Furse demonstrated how, by using such a bilingual cable, data could be easily transferred from the Firenex hub to a 1394a four-port hub from Belkin (Compton, CA, USA; www.belkin.com). Using this hub, peripherals such as the company's CV640, a 640 × 480, 120-frames/s camera, and a 1394a-enabled laptop were networked (see figure). In addition, Prosilica has developed software specifically to support the 1454 system from National Instruments (Austin, TX, USA; www.ni.com).