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Camera Link HS standard released

A new machine vision standard, Camera Link HS (CLHS), has been released at the Vision Show in Boston, US (8-10 May). The standard, which is being overseen by the AIA, supports 2.1GB/s bandwidth per cable allowing up to 16GB/s with a maximum of eight cables. It also provides real-time triggering functionality.

The standard grew out of HS Link, an interface originally developed by Teledyne Dalsa for its high-speed cameras that exceed the bandwidth capabilities of Camera Link.

Speaking to Imaging and Machine Vision Europe, Michael Miethig, chair of the Camera Link HS committee and technical manager at Teledyne Dalsa, commented that the first applications will be those exceeding the bandwidth of Camera Link, although he added that it is also designed for the lower end with a fibre optic connection offering 300MB/s.

CLHS also provides real-time triggering capability, similar to Camera Link – the standard has some of the features of the original Camera Link, but it is a separate standard and not backward compatible.

It has a trigger jitter of 3.2ns and a latency of around 100-300ns. This is ideal for line scan applications and simplifies system design, as the latencies can largely be ignored because they are so short.

The standard is also designed to take advantage of CMOS image sensors, with the ability for frame-by-frame control due to the high-speed uplink. ‘That’s new to the market with CMOS,’ said Miethig. CMOS technology allows regions of interest to be read out of the focal plane array to speed up the frame rate. Windowing can be changed for each frame with CLHS.

The CLHS committee is also offering an Intellectual Property (IP) Core Solution that implements the message layer of the CLHS standard, the reason being, according to Miethig, ‘to reduce the support cost’. He said that releasing the Cores will reduce development risk, reduce time-to-market, and make it possible for end-customers to design frame grabbers and cameras with low risk. ‘There are a lot of benefits to the Core; there’s lots of engineering effort in there,’ he said, adding that any bugs will be resolved collectively through the user base. The target release date for the IP Cores will be 31 May.

Future development work on the standard, according to Miethig, includes better design qualification to give assurance of product interoperability and cabling distance. It will also include a frame header packet, allowing the camera to tell the frame grabber which windows are being sent rather than being a slave to the frame grabber.

In a couple of years the committee will also look at higher density fibre optic connectors, Miethig said. ‘I think fibre optic will be the media of choice in a few years as the cost really starts to come down. And for long distance, fibre optic is cheaper than copper,’ he stated, adding ‘we’re hitting the limits of copper cabling in terms of bit rates’.

The Camera Link HS subcommittee is made up of camera, frame grabber and cable companies. The current participants are: 3M Company, Anafocus, Basler, Bitflow, Components Express, Gidel, Great River Technology, Intercon 1, JAI, Matrox, Mikrotron, National Instruments, PCO Imaging, Silicon Software, Stemmer Imaging, Teledyne Dalsa, and Toshiba Teli.

This release, the planned release of USB3 Vision at Vision 2012 in Stuttgart in November, and the relatively recent release of CoaXPress at the beginning of 2011, has seen three new machine vision standards introduced in reasonably quick succession. It will take time to determine how Camera Link HS and the other new standards will find their place in the market (see the feature article 'Setting standards', in the April/May issue of Imaging and Machine Vision Europe for further discussion on connectivity).

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