"Developing Real-time Video Applications with CoaXPress," A Presentation from Euresys

Copyright © 2017 Euresys 1
Jean-Michel Wintgens
May 2017
Developing Real-time Video
Applications with CoaXPress

Introducing Euresys

• Manufacturer of frame-grabbers and image processing software libraries
• Since 1989
• Staff: 45 people
• Head office in Belgium
• Sales offices in California, Singapore, China and Japan
• Specialize in image capture and camera control for machine vision and
computer vision applications
• Selling 25 K frame grabbers and 10 K software licenses per year
• Member of the AIA, EMVA, JIIA and the Embedded Vision Alliance
• Active member of the CoaXPress technical committee
Introducing Euresys

What is CoaXPress?

• A video transport standard for Computer Vision
• Camera – Frame Grabber Interface
• High data rate
• Up to 6.25 Gbps (8b/10b encoded: 625 MByte/s) over a single
coaxial cable
• Link aggregation: 8-connection cameras at 50 Gbps (5 GByte/s) are
available off-the-shelf
• 12.5 Gbps per connection under development
• Acquire images from the fastest and highest-resolution cameras
What is CoaXPress?

• Flexible and reliable cable
• Use standard coaxial cables
• Ease of integration
• Simplify cabling and reduce costs with a single coaxial cable for
• Data transfer
• Camera control
• Power
• Take advantage of robust connectors
• With a push/pull latching system for reliability in industrial applications
CoaXPress Benefits

• Standard 75-Ohm Coaxial Cable
• Asymmetric High Speed Serial Communication
• Connection Aggregation
• Use multiple cables to increase performance
• 1, 2, 4, or more
CoaXPress
Image /
Video
Control +
Trigger
Power over
CoaXPress

• Comparison with other interfaces
Bandwidth
Interface Bandwidth
GigE Vision/Ethernet 230 Mbyte/s
USB3 400 Mbyte/s
Camera Link 850 Mbyte/s
(1 x CXP-6)
625 Mbyte/s
(8 x CXP-6)
5000 Mbyte/s

• Comparison with other interfaces
Cable length
Interface Cable length
GigE Vision/Ethernet 100 m / 330 ft
USB3 3~5 m / 10~16 ft
Camera Link 6~10 m / 20~32 ft
(CXP-1)
130 m / 430 ft
(CXP-6)
40~80 m / 130~260 ft
(CXP-12)
20~40 m / 65~130 ft

• Adopted by Major Camera Manufacturers
CoaXPress Benefits

• Problem
• Trigger is asynchronous with any other traffic on the CoaXPress link
• Frame grabber sends the trigger packet (6 characters) to the camera
using 20.83 Mbps uplink
• Traffic is 8b/10b encoded
• Packet insertion at character boundary, one 10-bit character is 480 ns
• Potential jitter up to 7 x 480 ns = 3.4 µs
CXP Fixed-latency low-jitter camera triggering

CXP Fixed-latency low-jitter camera triggering
• Solution
• Measure the time  between
trigger event and sending trigger
packet (time unit = 2 ns)
• Send the delay  in the packet
• The camera waits (480 ns - )
before issuing the trigger
• Fixed latency: 7 symbols: 3.4 µs
• Jitter: < 4 ns

Camera Trigger
Up Connection
(No Additional Cable)
Up Connection
(Additional CXP-6 Cable)
Bit Rate 20.833 Mbps 6.125 Gbps
Latency 3.4 µs 20 ns
Jitter +/- 4 ns +/- 1.6 ns
Trigger Rate Up to 125 kHz
Up to 250 kHz*
Up to 2 MHz
* Single message trigger mode

Euresys CoaXPress Frame Grabbers

• Coaxlink: general purpose CoaXPress frame grabbers
• Up to four CoaXPress CXP-6 connections
• PCIe 3.0 (Gen 3) or PCIe 2.0 (Gen 2) x4 bus
• Feature-rich set of up to 20 digital I/O lines
• Extensive camera control functions
• Memento event logging tool
Euresys CoaXPress Frame Grabbers

Euresys Coaxlink Series
CoaXPress Configuration and camera bandwidth
CXP-6 DIN-1
1 x 6.25 Gb/s
= 625 MB/s
CXP-6 DIN-2
2 x 6.25 Gb/s
= 1,250 MB/s
CXP-6 DIN-4
4 x 6.25 Gb/s
= 2,500 MB/s
PCIe
Bus
PCIe 2.0 (Gen 2) x4
1,700 MB/s (sustained
bandwidth)
Coaxlink Mono
Coaxlink Duo
Coaxlink Duo
PCIe/104
Coaxlink Quad
PCIe 3.0 (Gen 3) x4
3,350 MB/s (sustained
bandwidth)
- -
Coaxlink Quad G3
Coaxlink Quad G3 DF

• Two-connection ruggedized
CoaXPress frame grabber
• Ruggedized board for
industrial and transportation
embedded applications
• Small stackable PCIe/104
form factor
Coaxlink Duo PCIe/104-EMB

• Two-connection ruggedized CoaXPress frame grabber
• Extended temperature range: -40 to +85°C / -40 to +185°F
• Sustained shock: 40 g/11 ms (all axes – half-sine and saw tooth)
• Optional conformal coating
• Two CoaXPress CXP-6 connections: 1,250 MB/s camera bandwidth
• PCIe 2.0 (Gen 2) x4 bus: 1,700 MB/s delivery bandwidth
Coaxlink Duo PCIe/104-EMB

• Feature-rich set of IO
• High-speed differential inputs: Quadrature motion encoder
support up to 5 MHz
• Isolated current-sense inputs: 5 V, 12 V, 24 V signaling
voltages accepted, up to 50 kHz, individual galvanic isolation
up to 500 VAC RMS
• Isolated contact outputs
• High-speed 5V-compliant TTL inputs/LVTTL outputs
Coaxlink General Purpose IO

• C2C-Link is able to synchronize cameras connected
• To the same Coaxlink card
• To different cards in the same PC
• To different cards in different PCs
• Distributes camera trigger at up to 2.5 MHz
Coaxlink C2C-Link

• Memento event logging system
• Memento records an accurate log of events related to the camera,
the frame grabber and its driver as well as the host application
• It provides assistance during application development and
debugging, as well as during operation
Coaxlink Memento

• Memento event logging system
• It provides a precise timeline of
time-stamped events, with
context information
• It is non-intrusive and works
with all Coaxlink cards
in the PC
Coaxlink Memento

• AMD DirectGMA
• Direct transfer of image data from Coaxlink to GPU memory
• Compatible with the AMD FirePro W5x00 and above
and all AMD FirePro-S series products
• Sample program available
• NVIDIA GPUDirect for Video/Cuda
• Significant performance improvements
in data transfer times for applications
Coaxlink Image transfer to GPU

• Windows and Linux drivers
• x86 and x86_64 architectures
• AArch64 64-bit ARM architecture for Linux
• User-level API
• Dynamic libraries to use with ISO-compliant C/C++ compilers
• .NET assemblies to use with .NET framework 2.0 and above
Drivers

Applications

• For applications where
• Use of coaxial cable is prevalent
• Longer cable length is required
• Defense applications
• Security applications
• Medical applications
Applications

• For applications requiring
• High data rates
• High frame rates
• Long cable lengths, greater
cable reliability and flexibility
• Flat panel display inspection
• Solar glass inspection
• Glass inspection
Applications

• For applications requiring
• High resolution & frame rate
• Synchronized operation of
multiple cameras
• Complex lighting control
Strobed, IR, Multi-spectral…
• Consistent real-time timing
• Automated Optical Inspection
• Printing inspection
Applications

Applications

• Accurate synchronization between frame grabber and OS time
• Challenge
• Different start time
• Clock drift
• Low frequency drift variations
• Temperature
• CPU load
• Power supplies
Accurate Time Synchronization
OS Time
FGTime

• Solution
• Synchronization model
• Taking into account the drift
between clocks
• Robust against low frequency
drift variations
• Monitor the synchronization error
and react if it varies
• In practice
• Error < 2 µs (with clock precision 1 µs)
Accurate Time Synchronization
OS Time
FGTime

Summary

• A powerful standard for computer vision
• Simple and cost-effective
• 75 Ohm coaxial cable with industrial connectors
• Highly Integrated
• Data, control, real-time trigger, and power in the same cable
• Adopted by major camera manufacturers
• Highest rates
• 8 x CPX-6  50 Gbps  5 Giga Pixels/s
Summary

• A Powerful standard for computer vision
• Longest cables
• 130 m with CXP-1
• 40-80 m with CXP-6
• Reliable
• Resilient protocol
• A progressing standard
• Towards Higher Rates: CXP-12…
Summary

• Coaxlink: general purpose frame grabbers
• Up to four CoaXPress CXP-6 connections
• Choice of PCIe 3.0 (Gen 3) or PCIe 2.0 (Gen 2) x4 bus
• Feature-rich set of up to 20 digital I/O lines
• Extensive camera control functions
• Memento Event Logging Tool
Summary

Thank you for your attention!

CoaXPress Details

CoaXPress – Comparison with other interfaces
Interface Bandwidth Frame rate
4MP camera
Cable
length
Trigger
jitter
GigE Vision 1.0 Gbps 25 fps 100 m
USB3 5.0 Gbps 90 fps 3 ~ 7 m
Camera Link Base: 2.0 Gbps
80-bit: 6.8 Gbps
-
180 fps
6 ~ 10 m ☺
CXP-6
1x: 6.2 Gbps
2x: 12.5 Gbps
4x: 25.0 Gbps
142 fps
-
563 fps
40 m ☺

CoaXPress Down Link – Data Rates
Bit Rate (Gbps) Data Rate (MBps)
CXP-1 1.25 125
CXP-2 2.5 250
CXP-3 3.125 312
CXP-5 5 500
CXP-6 6.25 625
Pixel Rate
(Megapixel/s)
1 x CXP-6 2 x CXP-6 4 x CXP-6
8-bit pixel 625 1,250 2,500
10-bit pixel 500 1,000 2,000
24-bit pixel 208 417 833

• 20.833 Mbps Communication Channel
• Control the Camera
• Setup the camera
• Control the camera operation
• Real-Time Triggering
• Trigger the camera exposure
• Control the exposure time
• Reliable protocol
• Fixed latency/Low jitter
CoaXPress Up Link

• 24 V DC
• 17 W provided by the frame grabber on each connector
• 4 W cable loss budget
• 13 W at camera side
• Connection Aggregation
• 2 Connections: 34 W (26 W)
• 4 Connections: 68 W (52 W)
• Plug and Play
• Automatic detection of PoCXP support
• Over-current protection
Power over CoaXPress (PoCXP)

Cable length
Cable
Type
Manufacturer
Reference
CXP-1 CXP-3 CXP-6
Industry
Standard
Belden 1694A 130 m 100 m 40 m
Gepco VSD2001 140 m 110 m 44 m
Canare L-5CFB 118 m 88 m 34 m
Flexible Belden 1505F 80 m 60 m 23 m
Gepco VHD2000M 81 m 61 m 24 m
Canare L-3CFB 72 m 60 m 24 m
Thinnest Belden 1855A 55 m 55 m 25 m
Gepco VDM230 66 m 62 m 25 m
Canare L-2.5CFB 43 m 43 m 20 m

• BNC Connector
• DIN 1.0/2.3 Connector
• Robust push/pull latching connection
system for reliable industrial applications
• Since CoaXPress 1.1
• Multi-Connector Assemblies
75-Ohm Connectors

• 8b/10b Encoding
• Increase the reliability of the transmission
• Detect data transmission errors
• Forward error correction is considered for a future CXP version
Data Transmission Reliability

• Resilient Protocol
• Data Packets (image and control)
• 32-bit CRC checksum
• Redundancy: Replication of critical packet header data
• Image & Synchronization Information
• Trigger Packets
• Using special K-codes in the 8b/10b coding
• Redundancy: Character replication
• Message Handshake: Acknowledge and resend procedure

• Connection Test Mode
• Standardized method to validate a system
• Mandatory for all CoaXPress Frame Grabbers and Cameras

• Comparison with Camera Link
Interface
Bit Stream
encoding
Resilient
Protocol
Connection
Test Mode
Camera Link No encoding No checksum No
8b/10b
32-bit CRC,
redundancy,
message
handshake
Mandatory

"Developing Real-time Video Applications with CoaXPress," A Presentation from Euresys

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