On the other hand, protocols designed specifically for machine vision, like Camera Link and Camera Link HS, directly support features that machine vision systems need, such as asymmetric data bandwidth and low-latency triggers or GPIO within the cable. They also tend to be simpler than general-purpose protocols.
Having choices can be a good thing. The newer machine vision-specific standards are becoming a necessity, especially for increasingly popular multi-camera systems. The parallel, point-to-point Camera Link protocol needs only one frame grabber per camera. These cards, and the connecting cables, don't come cheap, since Camera Link is essentially a closed standard specific to machine vision. Serial Camera Link HS transfers far more bits per wire, so it handles both traditional point-to-point configurations with a single camera and a single frame grabber, and different flavors of multipoint systems with multiple frame grabbers, multiple cameras, or both.
But six or eight is a lot of interfaces for camera and frame grabber vendors, making it tough to decide where to spend their R&D dollars. Not all frame grabber suppliers are thrilled at the prospect, since they usually provide more choices than camera makers. Some have said this many standards complicates the supply chain, dilutes R&D budgets, and confuses vision system designers and production engineers. Then there's the software investment problem, which makes protecting legacy applications a priority and provokes dread of the time, expense, and hassle needed to convert from one standard to another.
Although little is known yet about USB3 Vision, USB 3.0 is well understood and embraced by several machine vision camera makers, as well as some frame grabber suppliers. The 3.0 version is a lot faster than its predecessor, USB 2.0, and more deterministic, which is critical in real-time factory floor video networks.
At this year's Vision 2011 show in Stuttgart from November 8 to November 10, a special exhibition on international machine vision standards will feature USB 3.0 among others in a series of demonstrations that will attempt to unravel the confusion surrounding interfaces, according to a press release. I wish I could attend. I hope there will be presentations.