STANDARDS
Coaxpress gains fibre and 3D support
Chris Beynon, Active Silicon’s chief technical officer and technical chair of the Coaxpress committee, updates on the Coaxpress standard
T
he big update for Coaxpress was 2019’s v2.0. It added several new features, such as event packets, but
the headline change was the doubling of uplink and downlink speeds, with 12.5Gb/s now supported on each cable. Image sensors are getting larger and faster, so this allows Coaxpress to continue to support the very fastest cameras on the market. A typical four-cable product now operates at 50Gb/s. In February this year, the Japan Industrial
Imaging Association (JIIA) released Coaxpress v2.1. Te main addition here is support for the new GenDC standard, which makes Coaxpress the first of the machine vision standards to adopt it. GenDC – Generic Data Container – is a
GenICam module that defines how image data is represented, transmitted or received independent of its format. It can describe a simple rectangular 2D image, but it can also describe metadata attached to the image, or more complex formats such as 3D data. It’s the description of complex formats
that is the main benefit for Coaxpress. It would be a lot of work for Coaxpress, and all the other imaging standards, to each define how to represent 3D data, as an example. So everyone worked together to define GenDC, which does all the heavy lifting of how to describe such data. Now, with GenDC support in v2.1,
Coaxpress has full 3D support. In addition, when a new image format comes along in the future, there will be no need to up-issue Coaxpress to support it – as soon as GenDC defines the format, Coaxpress can use it.
Coaxpress-over-fibre JIIA has released a guideline document to support the use of optical media with the Coaxpress protocol. Tis means manufacturers of Coaxpress products can
maintain the investment they’ve made in Coaxpress IP, and offer customers real-time, deterministic behaviour they’re familiar with from Coaxpress. For many applications the copper coax,
at up to 12.5Gb/s per cable, continues to work very well, and gives a good balance for machine vision of camera speed, size, heat dissipation, cost and cable length. Most Coaxpress cameras, including those running at CXP-12, are too small to fit a typical QSFP optical connector, and the available small fibre optic solutions are generally very expensive. Having said that, some applications
benefit from fibre optic cables; for instance, if very long cables are needed – many tens or hundreds of metres – or if electrical isolation is required between the camera and the PC. Additionally, as speeds increase further,
such as 25Gb/s operation per cable, it’s inevitable that optical will win over copper. Terefore, it’s very important that Coaxpress
30 IMAGING AND MACHINE VISION EUROPE VISION YEARBOOK 2021/22
Active Silicon’s 4xCXP-12 FireBird Coaxpress frame grabber (PCIe Gen3 x8)
‘GenDC clearly allows the 3D camera vendors to make much faster cameras’
has fibre support, so it can leverage the investment going into high-speed fibre for Ethernet, while simultaneously maintaining the proven, real-time Coaxpress protocol. Both the addition of GenDC and the
fibre protocol are still very new, so it’s a bit early to say much about products. In terms of GenDC, it’s probable that 3D cameras will be the first to take advantage of this. Te higher speeds of CXP v2 have already allowed equipment providers to upgrade their products to use faster sensors. GenDC clearly allows the 3D camera vendors to make much faster cameras than the typical gigabit Ethernet products currently on the market. So, watch this space! O
@imveurope |
www.imveurope.com
Active Silicon
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