Compared to previous methods, data acquisition systems powered by vision systems and barcode readers offer greater consistency and easier setup for analyzing a wider range of applications. The following explains how this is achieved. Seeing is believing, so please carefully read the following technical specifications and application information to make it easier for you to implement next-generation vision/barcode equipment. Basic Information Basic one-dimensional barcodes consist of vertical lines of varying widths and spacing (such as those on product packaging). More complex two-dimensional (2D) data matrix barcodes store much more information in a two-dimensional format. A barcode is like a line in a text, while a 2D barcode is the entire text. Barcode-based information is used in product design and quality, inventory, lifecycle tracking, and logistics. The information contained in barcodes can be extended into software for control and automation, production lines, maintenance, procurement, customer support, resource planning, and automated warehouses. Because barcodes are not just a set of vertical lines, and more and more information is being crammed into increasingly smaller spaces, higher-performance machine vision systems and advanced reader technologies always provide assistance. In many applications, traditional barcodes can be effectively scanned by industry-standard automated product identification readers. However, many early product applications still require OCR/OCV (Optical Character Recognition/Optical Character Verification) to ensure the labels contain human-readable information. Carl Cerst, Cognex ID Project Manager, recommends using vision systems in industrial environments employing more complex 2D data matrix barcodes. Among numerous suppliers, Cognex recently claims that its products can read not only RSS character sets but also CS composite character sets, used on pharmaceutical packaging for product identification and tracking. A recently proposed US federal law mandates that each unit of medication include a barcode containing a report of drug safety issues. Pharmaceutical companies store information about their drugs (along with production dates and batch numbers) in a machine-readable format on labels, extending from drug production to the supply chain—from hospitals and pharmacies to consumers picking up prescriptions. 2D barcodes are increasingly being used in other industries such as semiconductors, printed circuit board manufacturing, consumer goods, and packaging, particularly for quality and batch tracking. To better track products throughout their lifecycle, the automotive and aerospace industries emboss or etch barcodes onto individual components such as gearboxes, drivetrains, and various accessories. (Imagine the value of recalling just 400 vehicles instead of 400,000.) Machine vision is convenient for reading more complex barcodes, especially those on metal parts, because: glossy, matte, and rough surfaces; variability in dot-sized precision; the effects of lighting; and the need to read at rates of 600–2000 barcodes per minute at specific angles make machine vision essential. Gerst explains that when dealing with large numbers of parts, machine vision with sophisticated algorithms and optics enables highly reliable reading of complex barcodes. Gerst said, "This is a huge opportunity for barcodes, allowing them to leverage IT infrastructure to help identify problems in production. With just a few measurements and related adjustments, it's easy to increase output by 50% or increase inventory turnover by 10 times per year." Delphi uses 2D barcodes. The automotive industry requires the labeling and tracking of all parts and components, which helps track ongoing operations and manage maintenance. Delphi has installed Microscan Quadrus EZ smart cameras on some of its production lines to read click data matrices on components used in new anti-lock braking systems produced at its Juarez, Mexico plant. Craig Dring, a systems integration engineer at a barcode company in Centerville, Ohio, said, "The ability to identify and recall specific vehicles with these defective parts will significantly mitigate the impact of recalls throughout the supply chain." Delphi decided to use click tags as the data matrix symbol in this application to ensure the tagging remains effective throughout the component's lifecycle. Dring says, “When reading challenging 2D matrix codes, the robust and intelligent new cameras technically outperform some of the most sophisticated vision systems,” and require no additional external lighting. Dring considers the Quardrus EZ to be “the only reader technology he’s found capable of decoding these challenging click symbols, especially at such high speeds,” and also more cost-effective than other vision systems. Setting up the device is as simple as aligning the locator’s template with the symbol and pressing the “EZ” key; the software, lighting, and decoding algorithms are all built-in (like some vision systems). The application simultaneously monitors the degree of degradation in mark quality, alerting operators when it falls below a certain threshold, allowing them to inspect the mark system before problems arise. However, Mark Sippel, vision product marketing manager at Omron Electronics, says, “There wasn’t that much technology involved; it was just about training consumers. I heard people say, ‘I’ve never heard of a vision system doing this much for under $10,000.’” Sippel is describing a dark period for machine vision when it was considered too complex and expensive to be considered. Omron claims its V530-R180 series 2D barcode readers offer the steepest angle—60 degrees—for reading 2D barcodes imprinted on pins. Cognex's Gerst adds that vision system vendors have extensive experience in interfaced to programmable controllers and the input/output modules required for various industrial applications, "and we know how to process the data once it's acquired." The fields of communication, data acquisition, and analysis have accumulated rich experience in automation and control technologies and application projects. For example, National Instruments' compact vision system (CVS-1454), [an August 2003 product], is designed for embedded applications, allowing users to acquire images from multiple cameras via three FireWires. Software like Vision Builder for Automated Inspection or LabView can integrate barcode inspection into machine vision. Communication considerations vary depending on device performance, the amount of data transmitted, and user experience. See the appendix for more information on this topic. The range of options extends from simple sensors to high-end systems; new applications are designed daily, some highly integrating control systems far beyond traditional inspection or quality control. Chesapeake Science, using PID algorithms, is one example. For instance, PVI Systems, a provider of alliance solutions with National Instruments, recently incorporated vision technology as part of a closed-loop system for tension control in wire rope production. Doug Wilson, president of PVI Systems (East Lyme, Connecticut), opted for a vision system that provides feedback rather than a complex array of specialized sensors precisely aligned with the moving wire rope. Chesapeake Science (Stonington, Connecticut) uses a fiber optic sensing system to determine the position of markers as the wire passes through a 3x4-inch field of view. This inspection ensures each unit is of the correct length. Information is fed from a frame acquisition unit into PID-based software to adjust up to 14 actuators for tension/length control, ensuring the load is properly within the finished product range. Tension adjustment allows the control system to align the markers on all wire ropes. The system also uses data acquisition and counting/timing cards to monitor three decoders and two tension sensors. “We did a lot of work on the vision aspect; it felt like a new exploration – the first time we’ve used machine vision as feedback for a PID closed loop,” Wilson explained. “Vision systems are typically used for inspection and measurement, but in this application, the applications for machine vision localization are much broader than initially proposed, and we completed the project design in three days.” A PC from National Instruments with LabVIEW and Imag Vision software served as the controller. An STC400 camera was from Sentech. The Imag-1407 frame acquirer, PCI-6025E MIO, and PCI-6601 counting/timing cards were all provided by National Instruments. Pierre Alliaume, coordinator at Capalux ElectroSolutions, said that in quality control applications, a DVT Smartlmage Legend 540 vision sensor inspects the printed lettering on the top and sides of the bottle caps to check for proper sealing. Feedback from the Capalux-Pechiney production line is used to push defective caps off the line via a conveyor "pin" and a burst of air. A Capalux production site in St-Cesaire (Quebec, Canada) has a production rate exceeding 700 caps per minute. Alliaume, a systems integration engineer at ElectroSolutions (Quebec), says the above photos are deceptive: they are blurred when in motion, making individual caps invisible to the naked eye. Phone Cards The software for analyzing images is just as important as the connected hardware. Conversions, located in Glen Ellyn, Illinois, combines hardware and software in an application that uses Matrox Imaging Library's Optical Character Verification (OCV) and a Model 1394 camera equipped with a barcode module, with Travel Tags verifying phone cards produced at a rate of 850 cards per minute. Project manager Dave Nay says the project applies 100% verification that the printed barcodes and serial numbers match the data on the magnetic stripe. It uses Lomax, one of the top 10 standard software developed by Civision-Conversion's division, to simplify setup. Choosing a Supplier and Technology How should you choose a supplier and technology? Does your team have the expertise (proficient in using the equipment and able to deploy it in applications after half a day or less of intuitive learning) or should you hire a systems integration engineer with expertise in high-end technologies or someone who can meet your specific application needs? After analyzing supported vision technologies, supplier partners, application project experience, read rates, and lifecycle costs, you should be able to "see" what is best suited for your machine vision and barcode reader.