CoaXPress (CXP) is a

digital Digital usually refers to something using discrete digits, often binary digits. Businesses *Digital bank, a form of financial institution *Digital Equipment Corporation (DEC) or Digital, a computer company *Digital Research (DR or DRI), a software ...

interface standard developed for high-speed image data transmission in

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

applications. The name is a

portmanteau In linguistics, a blend—also known as a blend word, lexical blend, or portmanteau—is a word formed by combining the meanings, and parts of the sounds, of two or more words together.

of 'express' 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 has a wire conductor in the centre (D), a circumferential ou ...

' 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 ...

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 developmen ...

) and uses 75 ohm

coaxial cable Coaxial cable, or coax (pronounced ), is a type of electrical cable consisting of an inner Electrical conductor, conductor surrounded by a concentric conducting Electromagnetic shielding, shield, with the two separated by a dielectric (Insulat ...

s 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, also called a digicam, is a camera that captures photographs in Digital data storage, digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film or film stock. Dig ...

) 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 ...

in a

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

). 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 ...

s up to 6.25

Gbit The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as ...

/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 48 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 bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as ...

/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. Unlike Camera Link (which 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 u ...

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 c ...

), CoaXPress transmits data in packets 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 di ...

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

History

CoaXPress was developed by 6 companies, of who
Adimec
EqcoLogic (today:

Microchip Technology Microchip Technology Incorporated is a publicly listed American semiconductor corporation that manufactures microcontroller, mixed-signal, analog, and Flash-IP integrated circuits. Its corporate headquarters is located in Chandler, Arizona. ...

), an
Active Silicon
were among the biggest drivers, in 2008. The goal was to develop a successor for the

standard for high-speed and data-rich vision related communication. The first joint effort "internally known as Visilink" was stopped. The CoaXPress standard was first demonstrated in November 2008 at the "Vision" trade show. After a good reception, the standard writing consortium of industrial companies consisting of Adimec, Eqcologic, Active Silicon
AVAL DATANED
an
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. By this time th
Japan Industrial Imaging Association
has adopted CoaXPress to mature it into an official standard after which the first draft version 1.0 was presented in December 2010.

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 wave travelling in one direction along the line in the absence of reflections in th ...

of 75 Ω. The maximum transmission distance is depending on the bit rate and the quality of the cable. RG-11,

RG-6 RG-6/U is a common type of coaxial cable used in a wide variety of residential and commercial applications. An RG-6/U coaxial cable has a characteristic impedance of 75 ohms. The term, ''RG-6'', is generic and is applied to a wide variety of c ...

RG-59 RG-59/U is a specific type of coaxial cable, often used for low-power video and Radio frequency, RF signal connections. The cable has a characteristic impedance of 75 Ohm (unit), ohms, and a capacitance of around 20pF/ft (60pF/m). The 75 oh ...

, 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 is a miniature quick-connect/disconnect RF connector, radio-frequency connector for coaxial cable. It was introduced on military radio equipment in the 1940s, and has since become widely used in radio systems and as a common t ...

. 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.''CoaXPress Interface Moves into the Mainstream''
Vision Systems, Feb 2010

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 the

to the 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

) which involve automated acquisition and analysis of images. Some cameras and frame grabbers have been introduced which support and utilize the CoaXPress interface standard.''CoaXPress Interface Moves to Machine Vision Mainstream''
Ann R. Thryft, Design News, November 28, 2011. Retrieved December 1, 2012.

Implementation

At least two companies develop CoaXPress-compatible driver and equalizer devices:

(through its acquisition of EqcoLogic) and Macom.M23544: 12G Multirate Long Reach Equalizer with Reclocker
/ref> 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 instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

or frame grabber, requires dedicated

FPGA A field-programmable gate array (FPGA) is a type of configurable integrated circuit that can be repeatedly programmed after manufacturing. FPGAs are a subset of logic devices referred to as programmable logic devices (PLDs). They consist of a ...

IP core IP most often refers to: * Intellectual property, creations of the mind for which exclusive legal rights are recognized * Internet Protocol, a set of rules for sending data across a network IP or Ip or ip may also refer to: Businesses and organi ...

References

External links

*
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
{{Webarchive, url=https://web.archive.org/web/20211025095407/http://jiia.org/wp-content/themes/jiia/pdf/standard_dl/coaxpress/CXP-001-2021.pdf , date=2021-10-25 Japan Industrial Imaging Association Standard
The Future of Machine Vision Continued: the Future Standards Forum
Dec 19, 2012, adimec.com (older version archived on April 2, 2015). Computer buses Machine vision Physical layer protocols Serial buses Serial digital interface