Frame Grabbers Reach a New Limit in High-Speed Imaging

Thanks to their processing power and interfaces, PCs fast became the dominant choice for machine vision applications. Some industry insiders, however, wondered whether this rise would mark the beginning of the end for frame grabbers. But several decades after the first PCs hit the factory floor, the opposite remains true: Machine vision needs frame grabbers more than ever.

“Sensors are getting larger and faster, reaching 50 MP on a regular basis,” says Donal Waide, Director of Sales at BitFlow, Inc. “To cope with these volumes of data coming in, traditional methods are falling far behind.” For example, dual GigE Vision reaches a bandwidth near 200 MB/s, while USB3 Vision transmits data at 382 MB/s.

“To transport that data off the camera and onto the computer without interrupt issues, without loss of data, without delays, the frame grabber has proven time and again to be the only dependable method,” Waide says.

Figure 1: Equipped with a half-size x8 PCIe Gen 3.0 card, the Claxon supports up to four CXP-12 cameras. It also supports simultaneous capture from four 12.5 Gb/s CXP links and simultaneous communications to all cameras, which can be accurately synchronized or completely independent. Image courtesy of BitFlow, Inc.

CoaXPress 2.0 Doubles the Speed
Like all machine vision technology, frame grabbers have become faster and more adaptable. Their adoption is increasing, too, with a CAGR of 7.2 percent predicted between now and 2025, according to Grand View Research. Frame grabber manufacturer Active Silicon is seeing an even higher climb, reporting a growth rate of 25 percent last year.

“Our biggest market is Asia, where frame grabbers are used for flat-panel and consumer-electronics inspections that require high-speed, real-time imaging,” says Frans Vermeulen, Head of Sales and Marketing at Active Silicon. “We also see growth in markets like life-sciences, where microscopic and X-ray applications are common.”

CoaXPress 2.0, scheduled for release in late 2018, will usher in the next generation of frame grabbers. “The machine vision industry leveraged the Camera Link standard for all it could, resulting in dual-full and deca configurations devised to provide additional data paths and increase bandwidth,” says Sam Lopez, Director of Sales and Marketing for Matrox Imaging. “Even so, these configurations were not sufficient for market demands and ever-increasing data rates. What we are seeing now is the gradual move toward new, simplified standards such as CoaXPress 2.0 that will be able to sustain even higher throughput. Matrox Imaging fully expects this trend to continue in the coming years.”

CoaXPress currently supports a maximum data rate of 6.25 Gbps, but version 2.0 will add two more speeds: 10 Gb/s (CXP-10) and 12.5 Gb/s (CXP-12), supporting higher resolution cameras at double the speed. For example, a four-core cable can provide 4 GB/s of data continuously and reliably from camera to frame grabber.

The uplink speed will be doubled for CXP-10 and CXP-12, enabling trigger rates of more than 500 kHz without requiring a dedicated high-speed uplink cable. The latest generation of CXP will also allow a single camera to send data to more than one frame grabber, even in different PCs.

Figure 2: The Matrox Rapixo CXP frame grabber features four connections that support interfacing to independent cameras and are adept at handling higher data rates through connection aggregation, allowing for data rates of up to 12.5 Gb/s per connector. Each Matrox Rapixo CXP connection includes PoCXP support to deliver power, command, and data over a single coaxial cable. Image courtesy of Matrox Imaging.

Another enhancement to the standard is the addition of GenICam-compliant event packets, which allows the camera to signal events to the PC. Trigger events include those coming from an encoder or a strobe. Additionally, CoaXPress 2.0 will add support for 3D data formats that have been recently added to GenICam. The standard’s higher speeds mean greater flexibility in system design and reduction of total system cost. For example, CXP-10 exceeds the Camera Link full configuration, swapping out two expensive Camera Link cables for a single coaxial cable. Meanwhile, use of one CXP-12 connection instead of two CXP-6 connections translates to fewer cables.

The upgraded standard is prompting frame grabber manufacturers to release product accommodating it. In Q1 2019, BitFlow will unveil the Claxon (Figure1). Equipped with a half-size x8 PCIe Gen 3.0 card, Claxon supports up to four CXP-12 cameras. It also supports simultaneous capture from four 12.5 Gb/s CXP links and simultaneous communications to all cameras, which can be accurately synchronized or completely independent. BitFlow’s StreamSync acquisition engine optimizes synchronization between acquisition and direct memory access (DMA), while the buffer manager maximizes DMA channel efficiency. The frame grabber also offers full GenICam support for control and capture.

The Matrox Rapixo CXP frame grabber (Figure 2) also leverages CoaXPress 2.0, allowing for data rates of up to 12.5 Gb/s per connector and up to 50 Gb/s of aggregated bandwidth. Four connections support interfacing to independent cameras and are adept at handling higher data rates through connection aggregation. Moreover, each Matrox Rapixo CXP connection includes power-over-CoaXPress (PoCXP) support to deliver power, command, and data over a single coaxial cable, streamlining system configurations.

Meanwhile, the Matrox FDK complements the Matrox Rapixo CXP Pro by providing software developers and FPGA designers a more direct path to FPGA hardware, facilitating the offload and acceleration of image-processing functions from the host system. Using the Matrox FDK, developers can easily manage custom implementation using C/C++ languages and generate HDL code for use with Matrox Rapixo CXP Pro frame grabbers.

“These boards are designed to meet customer needs for integrating the control, format, and stream logic of various interfaces, as well as incorporating Matrox Imaging– or user-developed custom image pre-processing operations to offload from the host computer,” says Mathieu Larouche, Product Manager, Frame Grabbers and Camera Interfaces for Matrox Imaging.

Figure 3: The FireBird Single CoaXPress Low Profile link board (6.25 Gb/s), a four-lane Gen2 PCI Express frame grabber, offers front-panel I/O. Full GenICam support is offered, providing plug-and-play functionality, regardless of the interface. Image courtesy of Active Silicon.

Access to Affordability
Despite the introduction of CoaXPress 2.0, BitFlow’s Waide predicts that the need for more entry-level product will remain high. “Not everybody will adopt it for the same reason why we have customers out there who are looking for analog solutions,” Waide says. “Industries like semiconductor and glass inspection demand bigger and faster options, but others such as pill counting in a pharmaceutical plant or low-resolution web-inspection systems are quite content using lower-priced imaging and interface standards.”

Active Silicon recently released its low-cost FireBird Single CoaXPress Low Profile link board (6.25 Gb/s; Figure 3). The four-lane Gen2 PCI Express frame grabber is fitted with a micro-BNC connector and offers front-panel I/O. The company’s DMA engine technology, ActiveDMA, guarantees zero CPU usage, providing high-speed and low-latency image data transfers. Full GenICam support is offered, including a GenTL producer for data streaming and register accesses. The GenICam compatibility, also available with Camera Link frame grabbers, provides plug-and-play functionality, regardless of the interface, according to Vermeulen.

The Future of Frame Grabbers
Although demand for frame grabbers continues to rise, some traditional frame grabber manufacturers foresee significant technology changes on the horizon. “The majority of our customers are transitioning from point-to-point connections to networked video and looking at new ways to deploy frame grabbers,” says Jonathan Hou, CTO of Pleora Technologies. “Our external frame grabbers traditionally take existing image sources and convert the image feed into Ethernet or USB 3.0. As customers deploy networked systems, they’re now looking to frame grabbers to provide more than basic image capture and transmit.” 

Networking offers several advantages to the end-user. “Instead of a point-to-point connection, where it is one camera to one device, you can send data to multiple devices to process the camera image,” Hou says. “If you are doing an inspection application, for example, the processing computer can look at barcodes while another computer reviews color differences. This networked approach allows you to spread out the workload.”

Pleora also offers the eBUS SDK, which “makes it really easy for system integrators to interface with GigE Vision or USB3 Vision cameras and image sources from any vendor in a networked application,” Hou adds. “The toolkit is compatible with a variety of operating systems and simplifies the process of acquiring an image.”

This technology also opens the door for embedded vision, another growing trend in the industry. “You can run eBUS on Raspberry Pi and start doing machine vision on smaller embedded devices, creating a whole class of smart and IoT [Internet of Things] devices,” Hou says.

Looking ahead, Hou predicts changes for frame grabbers. “The frame grabber will evolve from just transport into network management technology,” he says. “It could be software running on the PC that’s capturing video directly through the network and doing some processing, or an external frame grabber like we offer today with added intelligence. The result is a whole network of vision devices.”