![]() ![]() More enhanced frame grabbers provide additional features such as on-board memory for local storage of image data. Basic frame grabber functionality includes the ability to receive image data from a camera and transfer it to host memory using either the programmed I/O or DMA methods. Frame grabbers can be more than simple data transfer units, so functionality refers to the feature set that the frame grabber provides. This method frees the CPU to concentrate on processing images and results in much higher frame rates. In the DMA method, on the other hand, the frame grabber is responsible for “writing” the pixels directly into the host memory. This procedure consumes much CPU time and limits the number of frames per second that the CPU can process. The programmed I/O method requires that the host computer “read” each and every pixel from the frame grabber and “write” it to host memory. There are generally two methods used: Programmed I/O and direct memory access (DMA). This refers to the ability of the system to process images and is affected by the method that the frame grabber uses to transfer images from the camera to the host computer’s memory. For example, a 32-bit peripheral component interconnect (PCI) bus interface operating at 33 megahertz provides only 1 gigabit per second of bandwidth whereas a PCI Express x4 interface provides 10 gigabits per second of bandwidth. On the host computer side, the bus type and bandwidth have to be considered as well. Its medium and full modes, on the other hand, require two 26-pin connectors and support 4.08 and 5.44 gigabits per second of bandwidth, respectively. For example, Camera Link’s base mode requires a single 26-pin connector and supports up to 2.04 gigabits per second of bandwidth. On the camera side, the type and number of connectors as well as the electrical characteristics have to be considered. There are several factors to be evaluated in selecting the interface. ![]() The interface is the physical and electrical connection scheme of the frame grabber that links the camera to the host computer. For example, if a 12-bit high-definition camera operating at 30 frames per second with a resolution of 1,920 by 1,080 pixels is being used, then a data rate of 1,920*1,080*30*12 = 746.48 megabits per second needs to be sustained. Bandwidth refers to the amount of data that the frame grabber has to be able to acquire from the camera and transfer to the host computer. Source: Edmund Optics Choosing the Right Frame Grabber Choosing the right frame grabber for a given application depends on many variables: The Camera Link HS interface is designed from a system point of view, ensuring that CMOS sensor technology can be fully exploited while providing low-cost cameras and frame grabbers that meet the ease of use, flexibility and data reliability demanded by customers.The creation of a machine vision system involves many elements, such as the host computer, camera and frame grabber. ![]() IP Cores Available for Quick, Low-Cost Development.Multi-Vendor Compliant Components Available.Copper or Fiber Optic Cables from 15 to 300+ meters in length.Scalable Bandwidths from 1,200 to 80,000 MB/s.Dedicated communication channel supports data rates up to 3.125 Gbits/s.Ultra-compact, field-proven 26AWG CX4 cable and connector. ![]() CameraLink HS Interface – is the next-generation image acquisition interface.The CameraLink HS interface takes the key strengths of Camera Link and adds new features and functions to meet customer’s demands today and tomorrow. Its low latency, low jitter, real-time signals between a camera and a frame grabber carry image data and configuration data. Camera Link HS cables are designed to specifically meet the demanding needs of vision and imaging applications. As a group, we are working with the Camera Link HS subcommittee to bring reference designs and a more complete specification to the table for industry use as the next generation Machine Vision interface. The CameraLink HS interface has become a new machine vision connectivity standard. KAYA Instruments (Intellectual Property). ![]()
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