Drives & Controls April 2022

38 n MACHINE VISION April 2022 www.drivesncontrols.com Decentralised designs offer clear benefits for vision systems M achine vision is a real game- changer for many industries. Applications range from quality assurance to track-and-trace. 2D and 3D cameras can replace a variety of sensors and help to automate many processes. Barcode reading, measuring of dimensions, monitoring of fill levels, identifying and tracking parts and monitoring production, are just a few of the applications for vision technologies. Greater automation and optimisation result in higher efficiencies, quality and throughput, fewer reworks and improved customer satisfaction. As end-users seek more modular automation equipment, there is a clear trend towards decentralisation. Components and functions are moving from control cabinets to the field. In the future, there will be far fewer cabinets, and those left will be much smaller. Users will benefit from a reduction in cabling and costs as well as faster fault detection. What are the arguments in favour of decentralised architectures? And what are the challenges? First and foremost, there are the installation, warehousing, operational and diagnostics costs. When connecting field sensors and actuators to a controller, the signalling and power supplies can be expensive. But the costs actually start during planning and design, and continue through to the installation, including higher costs for larger control cabinets. An application- optimised, decentralised installation can cut the cost of installing power supplies by 30%. In addition, with centralised architectures, warehousing costs are higher because you need to stock a variety of components. If there are different requirements for machines and systems, then warehousing costs can soar. Implementing a decentralised design, with a plug-and-play approach, helps to avoid common problems, such as wiring errors. A standard installation requires high levels of concentration as workers cut, strip and crimp cables. Using pre-moulded, tested connector cables reduces the susceptibility to errors and shortens installation times. Diagnostics are another advantage of decentralised plug-and-play designs. In the event of a fault, there is no need to check wire colours in a complex terminal box. And, if machine or plant downtimes occur due to delivery delays for spare, or special parts or for hand-made cables, the cost planning ends up completely out of whack. Decentralised installations also have clear advantages for machine and system operation. For example, consider the heat in a control cabinet. Power components, such as power supplies, installed in cabinets suffer losses during operation, resulting in heat. If this is poorly dissipated, it can lead to performance losses and premature ageing of components. With decentralised installations, the power supply is mounted in the field. Its heat does not build up in a control cabinet, so cabinet cooling requirements are lower and the service lives of components are extended. Distance is another important factor. The longer a cable run between a power supply and an end-user, the greater the risk of voltage fluctuations. Decentralised switch-mode power supplies, such as Murrelektronik’s Emparro67, can supply power in the field while securing voltage on site in ambient temperatures of up to 85°C. Time-consuming and costly troubleshooting begins when errors result in plant standstills. Has there been a power outage? Is there a broken sensor? Troubleshooting is easier in decentralised systems. Thanks to LEDs and port-specific diagnostics on each module, errors can be found quickly, reducing downtimes. These benefits are available for vision applications such as camera-based signal processing. Large systems, or even entire production lines, can be involved, as in logistics operations or camera-controlled quality inspection of components. This is where decentralised installations come into their own – especially when it comes to fitting new components or retrofitting existing ones Often, these systems cannot be integrated easily into existing infrastructures. Camera systems require much more powerful data connections than classic sensors and need component space in control cabinets. With modular plug-and-play architectures, vision systems can be commissioned quickly and flexibly. The modules can provide detailed diagnostics that can cut downtime. Efficient power supplies and reliable data comms are key to any good installation. n Decentralised architectures can have many advantages for machine vision installations, especially in areas such as installation costs and space requirements. Carl Tyler, Murrelektronik’s vision systems project manager and sales manager for the north of the UK, outlines some of the potential benefits. The paths for Ethernet communications, power and IO in a typical decentralised machine vision application. The trigger and encoder signals are carried via the same daisy-chained cables as the 24V power supplies.