CoaXPress (CXP) is a

digital Digital usually refers to something using discrete digits, often binary digits. Technology and computing Hardware *Digital electronics, electronic circuits which operate using digital signals **Digital camera, which captures and stores digital i ...

interface Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * ''Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Inte ...

standard developed for high speed image data transmission in

machine vision Machine vision (MV) is the technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision refers to m ...

applications. The name is a

portmanteau A portmanteau word, or portmanteau (, ) is a blend of wordsexpress train An express train is a type of passenger train that makes a small number of stops between its origin and destination stations, usually major destinations, allowing faster service than Local train, local trains that stop at most or all of the s ...

) and '

coaxial In geometry, coaxial means that several three-dimensional linear or planar forms share a common axis. The two-dimensional analog is ''concentric''. Common examples: A coaxial cable is a three-dimensional linear structure. It has a wire conduc ...

' to emphasize CoaXPress is faster than other standards (e.g.

Camera Link Camera Link is a serial communication protocol standard''Specifications of the Camera Link Interface Standard for Digital Cameras and Frame Grabbers, Version 1.1'' Automated Imaging Association, Jan 2004 designed for camera interface applications b ...

, or

GigE Vision GigE Vision is an interface standard introduced in 2006 for high-performance industrial cameras. It provides a framework for transmitting high-speed video and related control data over Ethernet networks. The distribution of software or development, ...

) and uses 75 ohm

coaxial cables Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a ...

as the physical transmission medium. CoaXPress is mostly used in digital imaging applications but it is also suitable for high-speed transmission of universal digital data. A 'device' that generates and transmits data (e.g. an industrial

digital camera A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile device ...

) is connected with one or more coaxial cables to a 'host' that receives the data (e.g. a

frame grabber A frame grabber is an electronic device that captures (i.e., "grabs") individual, digital still frames from an analog video signal or a digital video stream. It is usually employed as a component of a computer vision system, in which video frames ...

board Board or Boards may refer to: Flat surface * Lumber, or other rigid material, milled or sawn flat ** Plank (wood) ** Cutting board ** Sounding board, of a musical instrument * Cardboard (paper product) * Paperboard * Fiberboard ** Hardboard, a ty ...

in a

computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...

). The CoaXPress standard 1.0 and 1.1 supports

bit rate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction w ...

s up to 6.25

Gbit The bit is the most basic Units of information, unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a truth value, logical state with one of two possible value (computer sc ...

/s per coaxial cable and the new 2.0 standard supports

s up to 12.5

/s per coaxial cable from the 'device' to the 'host'. The number of cables is not limited by the standard. Some recent CoaXPress cameras and frame grabbers use 8 coaxial cables providing a maximum image data rate of about 4.8 GB/s. The older

standard can only carry up to 850 MB/s. A low speed uplink, operating at up to 41.6

Mbit The megabit is a multiple of the unit bit for digital information. The prefix mega (symbol M) is defined in the International System of Units (SI) as a multiplier of 106 (1 million), and therefore :1 megabit = = = 1000 kilobits. The megabit h ...

/s is available to control the 'device' or for triggering. A CoaXPress 'host' can supply 24 V over the coaxial cable up to 13 W per cable. The CoaXPress standard requires that both the 'device' and the 'host' support

GenICam GenICam (abbreviated for Generic Interface for Cameras) is a generic programming interface for machine vision (industrial) cameras. The goal of the standard is to decouple industrial camera interfaces technology (such as GigE Vision, USB3 Vision, ...

, a standardized generic programming interface. Other than

that is built upon pure

LVDS Low-voltage differential signaling (LVDS), also known as TIA/EIA-644, is a technical standard that specifies electrical characteristics of a differential, serial signaling standard. LVDS operates at low power and can run at very high speeds ...

with no

transport layer In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end ...

, CoaXPress transmits data in packets (cf.

network packet In telecommunications and computer networking, a network packet is a formatted unit of data carried by a packet-switched network. A packet consists of control information and user data; the latter is also known as the ''payload''. Control informa ...

) using

8b/10b encoding In telecommunications, 8b/10b is a line code that maps 8-bit words to 10-bit symbols to achieve DC balance and bounded disparity, and at the same time provide enough state changes to allow reasonable clock recovery. This means that the diff ...

and provides CRC. CoaXPress competes with the Camera Link HS standard by the

Automated Imaging Association Automated Imaging Association (AIA) is the world's largest machine vision trade group. AIA has more than 350 members from 32 countries, including system integrators, camera, lighting and other vision components manufacturers, vision software prov ...

History

CoaXPress has been developed by 6 companies, of whom Adimec, EqcoLogic (today:

Microchip An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny M ...

) and Active Silicon were among the biggest drivers, in 2008. The goal was after the failure of Visilink to develop a successor for the

Camera link Camera Link is a serial communication protocol standard''Specifications of the Camera Link Interface Standard for Digital Cameras and Frame Grabbers, Version 1.1'' Automated Imaging Association, Jan 2004 designed for camera interface applications b ...

standard for high-speed and data-rich vision related communication. The standard was first demonstrated in November 2008 at the "

Vision Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain un ...

" trade show. After a good reception the standard writing consortium of industrial companies consisting of Adimec, Eqcologic, Active Silicon, AVAL DATA, NED and Components Express was formed early 2009. During the next Vision in 2009 the consortium was awarded the VisionAward for their efforts to further the cause of (machine) vision applications. ''CoaXPress wins the Vision Award 2009'' Retrieved December 20, 2012 By this time the Japan Industrial Imaging Association has adopted CoaXPress to mature it to an official standard after which the first draft version 1.0 was presented in December 2010. ''CoaXPress standard gains approval'' Retrieved December 1, 2012

Cabling and connectors

The transmission medium for CoaXPress is

cable with a

characteristic impedance The characteristic impedance or surge impedance (usually written Z0) of a uniform transmission line is the ratio of the amplitudes of voltage and current of a single wave propagating along the line; that is, a wave travelling in one direction in ...

of 75 Ω. The maximum transmission distance is depending on the bit rate and the quality of the cable. RG11, RG6, RG59 and other cable types can be used. It is also possible to reuse existing coaxial cable when upgrading from an analogue to a digital camera system. The original connector for CoaXPress is a 75 Ω IEC 61169-8

BNC connector The BNC connector (initialism of "Bayonet Neill–Concelman") is a miniature quick connect/disconnect radio frequency connector used for coaxial cable. It is designed to maintain the same characteristic impedance of the cable, with 50 ohm and ...

. The smaller DIN 1.0/2.3 connector was added in CoaXPress 1.1, and the Micro-BNC connector was then added to CoaXPress 2.0 for the new speeds faster than CXP-6. Most of recent camera and framegrabber products use either DIN 1.0/2.3 or Micro-BNC connectors and the IEC 61169-8 BNC has become rather rare. Solutions with a 5W5 connector have also been demonstrated, but this is not officially supported by the CoaXPress consortium.http://www.vision-systems.com/articles/print/volume-17/issue-2/features/coaxpress-interface-moves-into-the-mainstream.html CoaXPress interface moves into mainstream Vision Systems Feb 2010http://www.componentsexpress.com/PDF/CoaXPress_cables.pdf CoaXPress cabling solutions

Variants

CoaXPress is a scalable standard and can be used for connections from 1.25 Gbit/s up to 25 Gbit/s and more. Note that the following chart represents typical practical cable lengths; the CoaXPress specification only specifies the electrical characteristics of CXP cables for each speed standard, it does not explicitly specify maximum lengths.

Low speed uplink

CoaXPress supports a low speed uplink channel from

to camera. This uplink channel has a fixed bit rate of 20.833

/s for 1.0 and 1.1 version of the standard and a bit rate of 41.667

/s for the 2.0 version of the standard. The uplink channel uses

. The uplink can be used for camera control, triggering and firmware updates. When using the multilane DIN 1.0/2.3 cabling solution an optional high speed uplink can also be used, allowing 6.25 Gbit/s uplink communication to the camera. This can be used for very accurate triggering.

Usage

The most common application is to interface cameras to computers (via a

) on applications (such as

Machine vision Machine vision (MV) is the technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision refers to m ...

) which involve automated acquisition and analysis of images. Some cameras and frame grabbers have been introduced which support and utilize the CoaXPress interface standard.http://www.vision-systems.com/articles/2011/05/coaxpress-standard-camera-frame-grabber-support.html 'CoaXPress standard gets camera, frame grabber support'' May 31, 2011 by Andrew Wilson Vision Systems Design magazine Retrieved November 28, 2012http://www.vision-systems.com/articles/2012/11/cameras-certified-as-compliant-with-coaxpress-standard.html ''Cameras certified as compliant with CoaXPress standard'' by Dave Wilson, Senior Editor Vision Systems Design magazine November 12, 2012 Retrieved December 1, 2012http://www.vision-systems.com/articles/print/volume-16/issue-12/features/looking-to-the-future-of-vision.html ''Product Focus - Looking to the Future of Vision'' by Andrew Wilson Editor Vision Systems Design magazine December 1, 2011 Retrieved December 1, 2012http://www.designnews.com/document.asp?doc_id=235998 ''CoaXPress Interface Moves to Machine Vision Mainstream'' by AAnn R. Thryft November 28, 2011 Retrieved December 1, 2012

Implementation

So far, there is just one company,

(through its acquisition of EqcoLogic), which develops CoaXPress compatible driver and equalizer devices. These devices must be used with FPGA devices, in order to implement CoaXPress standard protocol. Such standard implementation is executed using FPGA IP core, specially designed for this protocol, while it takes care of all the features defined by standard. Each side of the vision system, e.g.

Camera A camera is an Optics, optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), ...

or frame grabber, requires dedicated

FPGA A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturinghence the term '' field-programmable''. The FPGA configuration is generally specified using a hardware de ...

IP core In electronic design, a semiconductor intellectual property core (SIP core), IP core, or IP block is a reusable unit of logic, cell, or integrated circuit layout design that is the intellectual property of one party. IP cores can be licensed to ...

References

External links

* {{Official website, http://www.coaxpress.com/
CoaXPress standard 1.0
Japan Industrial Imaging Association Standard
CoaXPress standard 1.1
Japan Industrial Imaging Association Standard
CoaXPress standard 1.1.1
Japan Industrial Imaging Association Standard
CoaXPress standard 2.0
Japan Industrial Imaging Association Standard
CoaXPress standard 2.1
Japan Industrial Imaging Association Standard * http://info.adimec.com/blogposts/bid/93362/The-Future-of-Machine-Vision-Continued-the-Future-Standards-Forum Computer buses Serial digital interface Physical layer protocols Machine vision