| Camera link has been a popular technology for | | | | Medium and Full configurations require two cables for |
| transmitting high speed image data from industrial | | | | the expanded data path. |
| vision cameras for over a decade. The specifications | | | | Camera Link Connectors |
| and standard designations are maintained and | | | | The connector styles for all configurations are the |
| administered by the Automated Imaging Association | | | | same, each is a 26 pin connector. The original |
| located in Ann Arbor Michigan, and is the global | | | | connector, developed by 3M, was termed a MDR |
| machine vision industry's trade group. | | | | connector. As industry demand for smaller and lighter |
| To its credit, the management of the technology has | | | | components grew, 3M created the "Shrunk D Ribbon" |
| been so successful, independent manufactures are | | | | connector design, which was termed a SDR |
| able to design and produce cameras, data acquisition | | | | connector. This design significantly reduced circuit |
| devices, and interconnect cables and components | | | | board space and camera interface real estate and |
| with full confidence that they will integrate seamless | | | | reduced weight. |
| with all other devices manufactured under these | | | | More recently, Honda Connectors Ltd has introduced |
| standards. | | | | their own version of a high density, miniature Camera |
| As Camera Link technology matured, changes in the | | | | Link connector which they termed a HDR connector. |
| standard were required to accommodate the | | | | Though this has caused some confusion for buyers |
| demands of the machine vision industry for higher | | | | tasked with purchasing cable and connector |
| data throughputs and increasingly compact, lighter | | | | components, the HDR from Honda, and SDR from |
| weight, components. The latter particularly critical to | | | | 3M Corporation are 100% compatible and |
| the robotics industry. The changes have resulted in a | | | | interchangeable. |
| somewhat bewildering array of terms used to | | | | Extending the AIA Standard |
| describe various interface configurations and cable or | | | | Some camera and data acquisition hardware |
| connector styles. The purpose of this article is to | | | | manufacturers have extended the bandwidth of the |
| provide the end user a quick synopsis of these terms | | | | Camera Link interface beyond the limits imposed by |
| to aid in proper component selection for their | | | | the AIA specifications. These formats extend the |
| projects. | | | | width of the "Full" configuration by reassigning |
| Camera Link Configurations | | | | redundant timing signals in such a way as to produce |
| The basic configuration is cleverly termed "Base" | | | | a data path width of up to 80-bits, further increasing |
| configuration and carries signals over a single | | | | the video bandwidth However, such "nonstandard" |
| connector/cable. The cable type was developed by | | | | configurations may lead to incompatibility issues with |
| 3M, and is referred to as a MDR ("Mini D Ribbon") and | | | | components manufactured within the imposed |
| uses a 26-pin male plug connector on each end and is | | | | standards. |
| optimized for Low Voltage Digital Signals (LVDS). The | | | | Summary |
| cable carries five (5) LVDS conductor pairs | | | | Although there appears to be a bewildering array of |
| transmitting twenty four (24) bits of serialized video | | | | configurations and connector styles, the majority of |
| data and four (4) timing signals. The connector also | | | | cameras using the camera link interface support the |
| carries four (4) LVDS discrete control signals and two | | | | simple Base Camera Link configuration with standard |
| (2) LVDS asynchronous serial communication channels | | | | MDR connectors. Typically Medium or Full |
| for communicating with the camera. The maximum | | | | configurations are only required for very high |
| video throughput is 2.04 Gbits/sec. | | | | resolution, high frame rate, applications. It is the |
| The "Medium" configuration doubles the video rate by | | | | limitations in architecture and costs of the imaging |
| adding an additional 24 bits of video data over a | | | | device that typically restrict performance, and not |
| second cable, increasing maximum throughput to 4.08 | | | | the data interface itself. |
| Gbits/sec. | | | | You will rarely encounter a camera device with an |
| The "Full" configuration adds another 16-bits of video | | | | excess of 2.0 megapixels operating above 30 frames |
| data, creating a 64-bit wide video path capable of | | | | sec and a 16 bit data output. Such a device requires |
| carrying 5.44Gbit/sec. | | | | a data rate of just under 1.0 Gbit/sec, easily |
| The Camera Link cables are designed with 26 | | | | managed by the Base Camera Link configuration limit |
| conductors, regardless of the configuration. The Base | | | | of 2.04 Gbit/sec. |
| configuration requires just one cable, while both the | | | | |