CoaXPress (CXP) is a popular digital interface standard developed for high-speed transmission of data, videos, and still images. Introduced in 2008, this interface has been used in industrial automation for years, with advanced machine vision and robotics applications following suit. It has been driven by reliability and simplicity, including its cables and connectors.
CoaXPress combines conventional coaxial cables with high-speed, serial data technology. It connects high-resolution cameras to frame grabbers (high-speed capture cards) using traditional coaxial cables.
For many years, this standard used COAX connectors and cables to support connectivity and older topologies. For example, Micro BNC’s circular connectors and Micro-Coax cables were typically used for older 6Gbps per-lane or link products. However, many of today’s I/O Faceplate connectors and cables must be robotic-friendly. (Micro-Coax is not ideal in these applications.)
More recently, CoaXPress has represented a booming market segment for advanced cables and connectors, including the quad small-form-factor pluggable (QSFP) and other pluggable connector types. QSFP is a compact, hot-pluggable transceiver used for data communications applications.
The data center industry is also proving an ideal and developing market for pluggable interconnect products, such as Twinax cables and QSFP connectors, which are gaining popularity. Twinax is a type of cable similar to coaxial cable but with two inner conductors instead of one.
There are several interconnect options available, including:
- Active optical cables (AOC)
- Direct-attach cables (DAC)
- Active optical modules (AOM)
The current 12.5Gbps per-lane speed rate typically supports four-lane links, trunked four links, or link aggregation using QSFP+ pluggable interconnect types.
The latest CoaXPress 2.0 standard is expected to increase the performance of machine vision systems by twice the speed and data rate. Twinax cables and optical connectivity are commonly used with these applications. CoaXPress-over-Fiber has also been designed as an add-on to the CoaXPress 2.0 specification, which provides a way to run the protocol over an Ethernet connection.
Japan Industrial Imaging Association (JIIA), which is dedicated to advancing technological innovation in industrial imaging, offers an informative document worth reading (check out JIIA’s “Optical Interface Guidelines for Coax Press”).
JIIA is developing 25 and 50G per-lane products, with expected 1, 2, 4, and 8X-link CoaXPress specifications using QSFP28 and QSFP56 connectors. However, they might switch to using some versions of the SFP56 and SFP112G links.
Camera Link is another high-end standard designed for camera interface applications, first launched more than twenty years ago in 2000. It was designed to standardize scientific and industrial video products, including cameras and frame grabbers. CameraLink already uses QSFP56 and QSFP112 connectors in AOCs, AOMs, and DACs. It has also used QSFP28 interconnect types more recently.
This group has remained relatively small and technologically focused on advancing. For instance, Camera Link High Speed (Camera Link HS) is an advanced interface standard for industrial cameras and systems that evolved from Camera Link.
Over time, several new types of higher-end cameras and sensor arrays have developed, driving the need for even greater network bandwidths and lengths. The goal with any digital interface protocol, of course, is to continually transmit larger amounts of image data at faster speeds. To this end, the industry has discussed the potential benefits of merging CoaXPress and Camera Link HS standards.
Many of the proponents for this proposed merger are from the CoaXPress consortium leadership. It has promoted its CoaXPress-over-Fiber IP products. However, a merged QSFP connectivity family would likely need new or revised Forward Error Correction (FEC), Common Management Interface Specification (CMIS) link requirements, and interoperability testing.
Currently, CoaXPress and Camera Link standards are different and have unique protocols and full-stack interfaces, both with better performances than basic Ethernet or GigEVision. However, CoaXPress and Camera Link undoubtedly intend to capitalize on using the newly developing IEEE 802.3 standards within their own protocols, particularly regarding connectors, cables, and modules.
The question remains: is merging the way to increase and strengthen global market share?
USB3 and USB4 are popular 10, 20, and 40G interfaces for use with frame-grabber I/O applications. There is already a large installed base of USB2 video frame-grabber end-users who are ready to move up to USB4 devices. What sets USB4 apart from its predecessors is the ability to deliver up to 40 gigabits per second of transfer speed.
These interfaces offer power and protocol options such as USB-like DisplayPort, HDMI, TB-4, MHL, and others. Depending on the system, the USB4 will rely on the reversible USB Type C connector and circuit pinout options using AOC or Twinax cable options.
The USB-C cable, connector, and controller chip are much less costly than CoaXPress or CameraLink parts. The Type C connector also has waterproof options and is extremely lightweight. The Type C Twinax cabling is also small and lightweight compared to other pluggable or Micro-Coax connectors.
What’s more: a small Spectra7 active electrical chip is mounted onto a minimal circuit board to improve the reach of Twinax cables. This type of cabling is similar to that used by AR VR video systems, which includes the rapidly growing Prosumer segment and gamer headsets.
The USB4s are already shipping, so the USB5-based product is likely already under development.
Final thoughts
Visit CoaXpress for the latest news on the potential merging of CoaXPress and CameraLink IO standards. It’s worth noting that other video frame-grabber interfaces, such as Hotaru’s OPT-C: Link and Mikrotron Eosens Fiber products, also have a small market share.
Although the demand for RJ45 and circular coax connectors is decreasing, orders for QSFP and USB-Cs are ramping up as these devices become the primary connectors. Most active-copper DAC cables with QSFP plugs are also now embedded with a chip (such as the Spectra7), enhancing QSFP links’ performance.
Suppliers of QSFP, SFP, SFP-DD, DSFP, QSFP-DD, OSFP, OSFP-XD data-center server, storage, and switch copper and optical-ink products can also expect demand to surge to support the quickly growing machine vision market segment.
Ultimately, cost and supply-chain control will affect how this market excels and changes over time.
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