New Cables and Two Cores in Parallel for Camera Link HS
The initial Camera Link HS standard was ratified in 2012 and it was updated to version 1.1 a couple of years ago – everything was kept the same, but it allowed for higher speeds on the connectors. The aim was to leverage the standard to take advantage of those higher speeds and get everything into one fiber.
Picture 1 | 14G will be in the next CLHS release enabling 11.4GBytes/sec in a single cable. Alysium is supporting the active optical cable and is soon to release their second generation which shrinks the connector that houses the optical engine. (Bild: Teledyne Dalsa Inc.)
CLHS built on the key strengths of Camera Link and added bi-directional GPIO and new triggering capabilities to meet customers‘ demands. Another CLHS goal is to allow on-the-fly changing of Window ROIs. And so, we came up with a remote DMA style of packet, which allows the frame grabber to know which pixels are included in each packet and therefore perform image preprocessing on the fly.
Active Optical Cables
High bandwidth cameras need many data lanes to transfer data from camera to frame grabber. So CLHS has a seven down, one up lane cable. Teledyne Dalsa currently uses each lane at 10G, which gives 1.2gigabytes/sec of uplink and 8.4gigabytes/sec of effective data bandwidth returned to the frame grabber. Rev 1.1 allowed 12.5G per lane on this cable, pushing the effective bandwidth to 10.2Gbytes/sec. This is still not enough bandwidth for upcoming products, and so 14G will be in the next CLHS release enabling 11.4GBytes/sec of throughput. Alysium and Hewtech have been supporting the active optical cable (AOC) and Alysium is soon to release their second generation which shrinks the connector that houses the optical engine and still maintains the 1W of power dissipation. Another change that has been discussed in the committee, is to allow CLHS to use 25Gbps optical technology. Studies confirm the current IP core available from the AIA is able to run at the required speed without change, and so the migration to the new speed will happen when the optical engines and the supporting FPGAs become cost effective.
Two Existing Cores in Parallel
CLHS leverages widely available ethernet technology. Ethernet is also going to 50Gbps per lane, and there are FPGAs out there that can support 50Gbps capability. So, one proposal in the committee is to parallel two CLHS cores, as they are today, put in extra little bit of logic to, concatenate those two cores into one. And then at the receiver end, split a concatenated signal into two receive signals. So, that’s a very simple change. But it’s a long way off. However, it’s good to know that we can keep reusing the core technology for many years to come without change, because it works.
Bild: Teledyne Dalsa Inc.
Inexpensive Fiber Optic Cables
Fiber optic cable is very inexpensive now. For example, fiber optic cable at 300m is the cheapest solution. So, if you want distance, low cost, and high data throughput beyond what copper cabling solutions provide, fiber is the answer. In addition, fiber cables are so thin, they are more easily routed than larger copper cables which also simplifies system design. Fiber doesn’t radiate emissions and it is EMI noise immune. So, it can be routed beside big motors, and data transmission won’t be affected. Using fiber optic physical layer cables in conjunction with CLHS is an ideal solution to use with robotic arms because fiber is very light and very easy to move and CLHS is single bit error immune. Fiber also has a lot of flex life as opposed to copper. Most people will choose the camera performance requirements first, but if you’re cabling driven, then CLHS is a great choice.
CLHS Cameras with AOC Cables
The Falcon4-CLHS camera models M4480 and M4400 can reach multiple thousands of frames per second in partial scan mode, and when using the sensor’s binning mode, can reach a very large pixel full well capacity of over 160Ke. The camera is using the AOC cable and takes advantage of its entire bandwidth. The camera’s small size and low power is enabled by the CLHS AOC cables. With the addition of these latest models, Teledyne Dalsa now offers a variety of CLHS-cameras ranging from the high-speed 11.2MP camera with a frame rate up to 609fps in full resolution, to the high-resolution 86MP camera with a frame rate up to 16fps. The company’s signature TDI line scan cameras reach to 16k pixels with 400kHz using CLHS.
