Thursday, March 31, 2011

Choose your standard

Is CameraLink on the way out? High-end camera maker Adimec thinks so and they explain the logic behind this statement in a white paper entitled “Vision connectivity interfaces.” (You will need to register for the download.)

This well-written document summarizes the pros and cons of the higher-end camera interface standards, GigE, CameraLink, CoaxPress and CameraLink HS. (In other words, 1394/Firewire and USB aren’t interfaces for those who are serious about machine vision.) The writers are careful to avoid hard-and-fast conclusions, preferring instead to suggest that interface choice should be a function of the application. But despite the efforts at objectivity it does seem that the real goal of the paper is to encourage movement towards the CoaxPress standard. (Of course, it may well be that this emerging standard really does offer the best all-round balance of performance and cost.)

If CoaxPress is new to you, the really neat thing about it is that it’s essentially good old fashioned coaxial cable. It’s capable of delivering up to 13W of power along with 1.25Gigabits of data per second over distances as long as 130m. It does need a framegrabber, but so do the other high-end interfaces, so that’s not really a negative, and as coax is flexible and robust it ought to help ensure good system reliability without costing the earth.

And what about CameraLink? Well as noted in the white paper, CameraLink has its strengths although many users are frustrated by the 10m cable length limitation. But the big problem is that it’s stopped evolving. There’s no roadmap to higher data rates, - CameraLink HS is not CameraLink 2.0 - and that means a CameraLink-based vision system has no upgrade path.

Choose your interface standard, but choose wisely.

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