Design News, March 2013

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Source: Bosch Rexroth Automation & Control Integrated motor drives create application benefits by distributing motion control and I/O on the machine, reducing wiring complexity, and the need for a central control cabinet. Modular Machine Design "Achieving greater modularity in machine building is an overall trend among automation machine builders. Customers are demanding greater flexibility and versatility of the equipment they are building with the shift away from machines being built to stock and sold off-the-shelf," said Robert Muehlfellner, director of automation technology for B&R Automation. "Many machines are now designed and built to order, and the challenge has been for the machine builder to come up with modular designs that can be combined in different configurations, for differing requirements." Modular design is increasingly an answer to the need for OEM machinery builders to create custom machinery. And while machinery builders have done a good job of doing this mechanically with machine sections that can be reused and reconfigured, the electronics in these types of systems has always been a difficult problem. The typical approach in the past has been a central electrical enclosure, with ample additional space in the control cabinet for any possible options even if individual systems often didn't require them. "Another important trend in modular design is the adoption of distributed I/O in both the IP67 format and now with motor-mounted drives or machine-mounted drives that are installed near a motor," Muehlfellner said. "Getting the power conversion out of the enclosure and out onto the machine is an advantage. This is a logical continuation from distributed I/O to drives, and extends what we have seen happening with I/O for several years now." This decentralized architecture also benefits from increasing use of a single cable connection for all of the individual modules of the modular machine. As machine modules are built mechanically, the electronic components (motors, integrated drives, distributed I/O, safety devices) can all be mounted on the machine close to the actuation point where the motion is happening. Connecting one machine module to the next can be accomplished using a single hybrid cable that carries the power and control voltages, communication, and safety signals. The modular approach has been advancing step-bystep from mechanical modular design, to electrical modular design using a single connecting cable, and following through on the software side with modular engineering process tools. Muehlfellner said motor-integrated drives make the most sense on machines with a larger footprint that implement a higher number of servo axes (four axes and up). Packaging, converting, and paper handling are good examples of the type of equipment that would benefit from this approach. The technology is available in a limited power range (1kW to 5 kW) although B&R sees that range expanding, in the future, in both directions. System architectures are becoming more modular by design and offer a logical combination of mechanical, electrical, and software modularity. The typical architecture includes a machine controller (a PLC or PAC) available in a variety of formats that incorporates the Powerlink master. It can be a brick-style, DIN rail mountable controller, a PowerPanel that incorporates the control with the HMI or a PC-based control solution. "The centralized control cabinet is in the way of achieving modular control systems where the machine designer would rather have those components close to the mechanical process," said Muehlfellner. "That is why remote I/O, safety I/O, and motor-drives are so critical to achieving that objective." B&R Automation recently introduced a new motorintegrated drive product that offers a local I/O connection point in addition to high-speed position latching inputs on the drive to eliminate any network latency. Using Powerlink as the Ethernet network backbone, every ACOPOS motor has a Powerlink connection for adding additional I/O and access to the B&R portfolio including IP67, a manifold controller, or safety I/O. The full spectrum of I/O application solutions can be connected directly to the integrated motor drives. Key technology in the new ACOPOS integrated motor drives is the local I/O expansion capabilities and the hybrid cable that enables the units to be used in either line or star architecture configurations. Safe Motion functions can also be added on a per-axis basis. Sercos III Multi-Ethernet Support "The most dominant trend that we see with integrated motor drives is the availability of multi-Ethernet support using sercos III as the Ethernet-based automation bus, providing an ability to connect to other different Ethernetbased buses," said Abdulilah Alzayyat, a product engineer for Bosch Rexroth. "If a customer has a different control, inte- Design News | march 2013 | www.d esign n –48–

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