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Choosing a Camera Interface: Qualify and Quantify
GigE versus other interfaces.
- Data rate is maximum theoretical (i.e., still includes overheads)
- Distance is over a single-segment of most common cabling for the given interface standard
- GigE Vision™ is predominantly based on Gigabit Ethernet (GbE) although it can be applied as is to the up and coming 10 GbE standard
- IEEE 1394 groups IEEE 1394a (S400 mode) and IEEE 1394b (S800 mode)
- USB 2.0 refers to Hi-Speed mode
- Camera Link® encompasses Base, Medium, Full and 10-tap configurations
By Sarah Sookman, Matrox Imaging
A is for analog; C is for Camera Link®; G is for GigE Vision™. Throw in IEEE 1394, LVDS / RS-422, and USB, and you've a got a simmering pot of interface soup. However, whether you're making a gumbo, chowder, or bisque will depend on the ingredients you put into it. Building a machine vision system is similar; your choice of components will affect the final product. This article presents a strategy to help you choose the best interface for your application. It also discusses some of the factors that will help define your choices: image fidelity, bandwidth, compactness and cables, and determinism. Refer to Table 1 for a brief comparison of the most popular camera interfaces: analog, Camera Link®, IEEE 1394, GigE Vision™, and USB. With a bit of knowledge and the right questions, you'll also be better prepared to help your camera vendor (and machine vision vendor) help you.
It All Starts With the Camera!
Machine vision rookies often ask vendors the same question: What frame grabber do I need? The vendors always give the same answer: it depends on your camera. So, your first step is to choose the camera that fits your needs in terms of resolution, data rate, and more. This exercise in itself may reduce the number of interfaces to consider.
| Attribute | Preferred (alphabetical order) |
| Best image fidelity due to signaling | Camera Link® GigE Vision™ IEEE 1394 LVDS/RS-422 USB |
| Best cable length (single segment) | Analog (standard) Analog (non-standard for lower clock rates) GigE Vision™ |
| Best vendor interchangeability | Analog (standard) |