Complete Technical Guide for Euresys Coaxlink CXP Capture Card

Euresys Coaxlink CXP-12 Acquisition Card

In the field of industrial machine vision, with the continuous increase in sensor resolution and frame rate, traditional Camera Link or GigE Vision interfaces have gradually become bottlenecks in system throughput. The CoaXpress (CXP) standard is becoming the preferred choice for high-end vision systems due to its advantages of transmitting data, control, triggering, and power (PoCXP) over a single coaxial cable, as well as link speeds of up to 12.5 Gbps. The Euresys Coaxlink series of acquisition cards is based on this standard, providing a rich product portfolio from single channel to eight channel, covering PCIe 2.0/3.0 buses, and integrating powerful I/O toolboxes, multi card synchronization, and onboard processing capabilities. This article systematically analyzes the technical points of the entire Coaxlink series from hardware architecture, signal processing, I/O configuration to actual selection, providing a practical selection and integration reference for visual engineers.

Overview of CoaXpress and Coaxlink Series

CoaXpress is an asymmetric high-speed serial communication protocol with a downlink (camera to capture card) rate of up to 12.5 Gbit/s (CXP-12) and an uplink (capture card to camera) rate of up to 20.83 or 41.6 Mbps, used for camera configuration and triggering. A single 75 Ω coaxial cable can support up to 100 meters (at CXP-3 speed) and supports PoCXP (Power over CoaXPress) for camera power supply, simplifying on-site wiring. The Euresys Coaxlink series collection cards are fully compatible with CXP 1.0/1.1/1.1.1/2.0 standards and offer the following main models:

Model Connection Number Maximum Bandwidth Bus Interface Heat Dissipation Method Special Features

Coaxlink Mono CXP-12 LH 1 1250 MB/s PCIe 3.0 x4 Passive Cooling Single Channel, Low Cost

Coaxlink Duo CXP-12 2 2500 MB/s PCIe 3.0 x4 Active Fan Dual Channel, Flexible Configuration

Coaxlink Quad CXP-12 4 5000 MB/s PCIe 3.0 x8 active fan with four channels, maximum speed

Coaxlink Quad CXP-12 JPEG 4 5000 MB/s PCIe 3.0 x8 Active Fan Onboard JPEG Compression, Dual Stream Output

Coaxlink Octo 8 5000 MB/s PCIe 3.0 x8 Active Fan Eight Channel CXP-6, Multi Camera

Coaxlink Quad G3 4 2500 MB/s PCIe 3.0 x4 active/passive optional CXP-6, supports multiple data streams

Coaxlink Quad G3 DF 4 2500 MB/s PCIe 3.0 x4 Active Fan Supports Data Forwarding

Coaxlink Quad CXP-3 4 1250 MB/s PCIe 2.0 x4 Active Fan Long Distance (>100 meters)

Coaxlink Quad 3D-LLE 4 2500 MB/s PCIe 2.0 x4 Active Fan Onboard Laser Line Extraction (3D Contour)

Among them, the CXP-12 model supports up to 12.5 Gbps per link, while the CXP-6 and CXP-3 correspond to 6.25 Gbps and 3.125 Gbps, respectively. All cards provide rich I/O interfaces (differential, TTL, isolated input/output) and powerful I/O toolboxes, supporting motion encoder access, trigger generation, and synchronous control.

Core hardware and bus performance

The core of the Coaxlink acquisition card is a high-performance FPGA (Xilinx Kintex Ultrascale or similar), responsible for CoaXpress physical layer protocol parsing, image data preprocessing (such as bit depth unpacking, Bayer decoding, LUT mapping), and DMA transfer. The onboard memory capacity ranges from 512 MB (Mono) to 2 GB (Quad/Ecto) for image caching and retransmission.

Bus bandwidth is the key bottleneck. For example, the Coaxlink Quad CXP-12 has a theoretical aggregate bandwidth of 5000 MB/s and requires PCIe 3.0 x8 (peak 7800 MB/s, effective 6700 MB/s) to fully utilize it. Duo and Mono use PCIe 3.0 x4 (effective 3350 MB/s), which is sufficient to meet their bandwidth requirements. If the x4 slot is inserted, the Quad CXP-12 will automatically slow down, so the motherboard slot specifications must be confirmed when selecting.

PoCXP power supply can provide 24V DC/17W power per channel, supporting camera automatic detection and overload/short circuit protection. It requires an external+12V power supply through the onboard 6-pin PEG power interface, which is boosted to 24V by the onboard DC/DC converter. The CXP-12 model uses Micro BNC (HD-BNC) connectors with a bayonet locking mechanism and good shock resistance; The CXP-6/3 model uses DIN 1.0/2.3 push-pull connectors.

Image acquisition and processing function

Coaxlink supports both planar and linear camera types, compatible with multiple pixel formats: Mono8/10/12/16, Bayer (RG/GR/GB/BG) 8~16, RGB/RGBA 8~16, YCbCr 4:2:2, and YUV. For 10/12/14 bit data, it can be unpacked into 16 bits and aligned with LSB or MSB.

The array camera control provides precise external hardware triggering (with adjustable delay and trigger frequency division), exposure control, and strobe output, supporting camera exposure/readout overlap to improve frame rate.

Line array camera control is Coaxlink's strength. It supports continuous web inspection and discrete object scanning. By using the Quadrature Decoder (QDC) tool in the I/O toolbox, A/B orthogonal encoder signals can be integrated to dynamically adjust the camera line rate based on motion speed, ensuring physical size consistency of pixels in the motion direction. The Rate Converter tool allows the encoder frequency to be converted at a ratio of 0.001 to 1000 times, enabling arbitrary pixel aspect ratios and easy correction to square pixels. In addition, Backward Motion Cancellation automatically pauses data collection when material retreat is detected, and resumes data collection from the disconnected location to ensure that there is no overlap or loss of images.