Which Interface ?

The two most common interface choices for digital cameras in machine vision are Cameralink and Firewire (IEEE 1394). However, gigabit Ethernet is quickly becoming the interface of choice because it offers compelling advantages over both Cameralink and Firewire.

Camera link is a parallel interface that offers very high data rates but is generally the most expensive interface option and the most difficult to integrate. Although camera link is faster than other interfaces, the cameras themselves are very often no faster than cameras operating on firewire. Camera link cables often cost hundreds of dollars, are non-standard between camera manufacturers, and must be matched to a frame grabber that typically costs over $1000. Also, Cameralink does not have an associated standardized communication protocol such as that associated with Firewire. This means that each different manufacturer's camera link cameras requires a higher degree of integration effort than, say, DCAM-compliant firewire cameras. There is little commonality between manufacturers. Because of cost, standardization, ease of use, and ease of integration issues, Serial interfaces such as Firewire and Gigabit Ethernet are rapidly gaining dominance over older interface types such as Cameralink.

Firewire is a better choice than Cameralink for most machine vision applications because of lower cost and the high degree of standardization in the hardware, the software interface, the computer interface. Cables are typically twenty or thirty dollars and can be purchased at your local computer store. No frame grabber is required, and many computers now include built-in firewire ports, so there are no frame grabber costs or connection issues. If a computer does not have a built-in firewire port, then a PCI or Cardbus firewire interface can be bought for less than a hundred dollars at your local computer retail outlet. In addition to the low-cost, standardized interface hardware associated with Firewire, there is also a standardized software interface for cameras called DCAM, or IIDC. This software interface standard means than any software that support IIDC (DCAM) camera will generally support all compliant cameras. This greatly reduces integration problems and provides true plug-and-play interoperability. All of Prosilica's firewire cameras are DCAM compliant (IIDC 1.30 and 1.31).

What about Gigabit Ethernet, you ask? A new camera interface standard called GigE Vision™, based on gigabit Ethernet, is the new interface of choice for machine vision cameras. Gigabit Ethernet, also called GigE, is a serial network standard that has very high bandwidth, very long cable lengths, and offers a low cost interface that is widely used in standard computer networking hardware. GigE, variously called Giga-E or Gig-E, offers attractive advantages over Firewire and Cameralink. For example, Firewire and Cameralink are limited to about 5 meters cable length. Gigabit Ethernet, on the other hand, offers cable lengths up to 100 meters long. Another advantage of Gigabit Ethernet is that the cables can be easily manufactured on-site. This is a great advantage for applications such as traffic monitoring, or security installations, where the cable length is often long and unknown until installation is in progress. The additional speed and cable length of Gigabit Ethernet are significant reasons why GigE Vision is quickly becoming the dominant machine vision camera interface. In fact, for new projects, GigE Vision is already the most popular camera interface. But there are more reasons than these that GigE is the camera interface of choice. One of the main draw-backs of Cameralink and USB 2 is that there is no standardized camera communication protocol. The Automated Imaging Association's GigE Vision standard provides a truly plug and play interface standard. All of Prosilica's gigabit Ethernet cameras are GigE Vision and Genicam compliant.

Prosilica manufactures a range of cameras for machine vision and industrial applications based on Firewire (1394 IIDC) and Gigabit Ethernet (GigE Vision) interface technologies. Please contact Prosilica for additional Information. www.prosilica.com

©Prosilica Inc. 2008