Introducing Camera Link HS: the best interface for demanding applications

Leveraging the key strengths of Camera Link to define the camera communication interface of the future

The interface that helps your application run faster and with fewer errors
Departing from the standpoint that a cameras is only as good as its connecting cable, a group of members from the Automated Imaging Association (AIA) has worked to overcome the speed limitations of the current Camera Link interface for line scan cameras.

Growing machine-vision needs wanting higher resolution and faster frame rates have placed a increased demand on bandwidth and the selected committee members of the AIA have worked to develop the next generation protocol standard to address, specifically, these increased needs. The concept is hosted by AIA and is being developed as a global standard where developmental priorities include: designing the interface from a system point-of-view, keeping a cap on costs while maintaining ease-of-use, flexibility and data reliability essential for robust use by customers and also attempting to eliminate the large number of cables needed for fast transfer speeds in multi-camera systems.

While carrying the Camera Link name and having a feature set that is very close to its namesake, the CLHS standard is a new type of interface sharing the same message types as the Camera Link protocols but differing in implementation and how messages are carried from one end of the cable to the other.

The best interface for demanding applications
According to Mike Meithig, committee chair and technical manager for Teledyne Dalsa, the challenge was to reduce wire count by putting video, communication, camera control, high-speed trigger and GPIO on a single wire. Meithig also explained that the committee needed to create a standard that offered greater reliability by eliminating the bit errors sometimes associated with Camera Link technology. "In Camera Link HS there are redundant trigger codes as well as video hardware resend to guarantee 100% reliable data," said Meithig, "The Camera Link HS SerDes can be implemented inside an FPGA with external equalizer ships from multiple suppliers and 100% reliable data is achieved with memory sizes that are small enough to be implemented inside the FPGA to reduce costs, size and power."

Supporting both multi-camera and multi-frame grabber systems and with protocols designed for a 10Gbps SerDes (downwardly scalable, if necessary) the new interface prioritizes messages and maintains the real-time low-latency and low jitter of Camera Link and so eliminating the need for a separate triggering cable.

Bob McCurrach, AIA's Director of Standards Development, said: "Camera Link HS is truly a real-time connection, there are no latency issues. Because Camera Link is so well known and widely used, we're sure to see Camera Link HS products multiply in the next year."

Point-to-point

Mike Miethig, Chair of the AIA Camera Link HS Standard Committee, explains the features and benefits of the new CLHS interface

Automated Imaging Association
AIA is the world's largest machine vision trade group comprising more than 300 members from 30 countries. Membership comprising representatives from various machine vision arenas and include system integrators, camera, lighting, vision software providers, researchers, manufacturers and distributors. Members of the subcommittee for research into CLHS include camera, frame grabber and cable companies working on the specification together.

SerDes (Serializer/Deserializer)
An integrated circuit transmitter/receiver that converts parallel data to serial data and vice versa. Commonly used in high-speed communications.

Field-programmable gate array
An FPGA is an integrated circuit designed to be configured by the customer after manufacturing

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