Another twist to camera interfaces

With various groups making plays for their preferred new standard – USB 3.0, CameraLink HS and CoaXPress – camera interfaces are in the news of late. Everyone talks about data rates and cable lengths - I’ve done my part, with “King of the (camera interface speed) hill” and “Everything you ever wanted to know about USB3.0” – but writing in the Adimec blog, Gretchen Alper offers another factor to consider: the cost of the cables. (“How to save cabling costs with new machine vision interfaces” August 29^th, 2012.)

Now I knew that CameraLink cables were expensive, but I hadn’t appreciated just how expensive in comparison to GigE, FireWire, USB 3.0 and CoaXPress. (Read Gretchen’s blog post to see the actual numbers.) CoaxPress is of course just plain old co-ax cable, which is why it’s so cheap. As backers of this new standard, Adimec aren’t exactly neutral, so I would expect them to have done their best to ‘spin’ the cable cost issue, but even so, the numbers are pretty startling.

I wonder if this might change your choice of interface next time you spec out a system?

King of the (camera interface speed) hill

Most of us were happy with FireWire-b and had no need of faster data rates. Then along came GigE and the bits flowed faster. If we needed real speed, like for those occasional linescan projects, there was always CameraLink.

But just as racing drivers always want more, so too do some machine vision people. Many of these are in the high speed web inspection niche, and they were starting to think that good old CameraLink might not be up to the job in a few years. So Dalsa started work on an interface they called “HSLink”.

This showed a lot of promise, but as Mike Miethig of Dalsa discusses in “Vision Market Touts Camera Link HS in Boston, Beyond” (Quality magazine, August 7^th, 2012,) it never really gained traction.

Fortunately for the speed freaks though, it did set the scene for CameraLink HS, which promises speeds of up to 2.1Gbytes/sec. Now that number might be hard to grasp, so I’ve put together a little graphic to show just how much faster than the older standards that is.

 

 

Now there are some important caveats. CameraLink speeds are complicated because they depend on whether it’s Base, Medium, or Full configuration. CameraLinkHS is much the same: there are three speed flavors, starting at a relatively paltry 300Mbytes/sec. And then, missing from my table, is CoaXpress.

CoaXpress boasts of up to 6.25Gbps, (which I suspect is gigabits rather than bytes,) so it’s not a s fast as CameraLink HS. More importantly, it’s not an AIA standard – it’s supported by the Japan Industrial Imaging Association – so whether it will prosper remains to be seen.

And what does this mean for the regular machine vision user? It means there’s virtually no limit to how fast you can shove those pixels down the pipe. The only question to consider is, how deep are your pockets?