In the late 1990s, a chipset called Channel Link (C-Link for short) was successfully born at the National Semiconductor Laboratory in the United States. The interface using this chip can increase the original transmission speed of only 250Mbit/s to 6.4Gbit/s after parallel processing, and the cost is almost unchanged. This makes it a perfect alternative to increase data throughput without increasing the number of cables.
Channel Link uses LVDS signaling mode (Low-voltage differential signaling), configured with 3, 4, or 8 chipsets to transmit data in parallel, and an independently configured synchronous clock for each channel. The 3-channel chipset has 21 single-ended inputs and outputs for the user interface, while the 4-channel chipset has 28 single-ended inputs and outputs. The 8-channel chipset has 48 single-ended inputs and outputs. It can be understood as two-way two-lane, two-way four-lane, and two-way eight-lane.
In 2000, under the promotion of the American Automation Industry Association (AIA), Channel Link evolved into an industry-standard specifically for scientific and industrial-grade visual products, including cameras, cables, and image capture cards, and thus transformed into Camera Link.
Camera Link is a version of Channel Link using a 4-channel chipset, with a total throughput of 2.38Gbit/s. On this basis, 3 chipsets can be placed in parallel, with a total throughput exceeding 7Gbit/s. Cameras have since been able to develop higher resolutions and higher frame rates.
Since its inception, the Camera Link interface has undergone various upgrades and transformations to adapt to increasingly higher data throughput requirements. As a result, we can see four versions of Base, Medium, Full, and Deca on the market. They vary in the data rates they transmit; some can even use two cables if needed.
The "Base" Camera Link configuration transmits signals over a single connector/cable. The cable is an MDR ("Mini D Ribbon") 26-pin male plug connector, optimized by 3M for LVDS signals. In addition to the 5 LVDS pairs transmitting serial video data (24 bits of data and 4 framing/enable bits), the connector also carries 4 LVDS discrete control signals and 2 LVDS asynchronous serial communication channels, to communicate with the camera. At the maximum chipset operating frequency (85MHz), basically
The setting produces video data throughput of 2.04Gbit/s (255MB/s).
The "Medium" and "Full" Camera Link specifications include higher bandwidth configurations providing an additional video data path through a second connector or cable. The "Medium" configuration doubles the video bandwidth, adding 24 bits of data and the same 4 framing/enable bits as in the "Base" configuration. This results in a 48-bit wide video data path with throughput up to 4.08Gbit/s (510 MB/s). The "Full" configuration adds another 16 bits to the data path, resulting in a 64-bit wide video path carrying 5.44Gbit/s (680MB/s).
With the further development of camera technology, the original Camera Link Full standard can no longer meet the image acquisition requirements of some ultra-high-resolution cameras, so the 8 unused bits in the Camera Link Full standard have been re-allocated and used, the new standard "Deca" Camera Link comes from this. Under the "Deca" standard, an 80-bit data path width can be generated through two connectors or a second cable, greatly expanding the data bandwidth and capable of carrying 6.8Gbit/s (850MB/s)
Currently, mainstream camera manufacturers in the industry use the term "Camera Link Deca" to refer to cameras and frame grabbers that are compatible with this mode. However, some manufacturers use "Extended Full" to refer to Deca configuration, and some still use "Camera Link Full" to describe Deca mode.
The early version of the Camera Link interface is shown on the left, using a 26-pin micro Delta Ribbon connector (MDR-26). The pins are easily skewed under the support of the middle plate. Starting from standard version 1.2, the shrink variant SDR-26 is allowed. As shown in the picture on the right, the pins tightly wrap the connection port and are not easy to loosen, making plugging and unplugging more reliable.
In the version 1.2 standard upgraded in 2007, the mini SDR ("Shrunk D Ribbon") connector (SDR-26) and power on camera link (PoCL) were introduced, thus giving birth to the Mini Camera Link interface and Power on Camera Link (PoCL for short) function.
The pursuit of higher transmission rates in industrial applications is eternal. How to increase data bandwidth, improve transmission reliability, and increase transmission distance while also reducing costs is an important part of industrial development.
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