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"No man is an island," says old-school, English, metaphysical poet John Donne. Now, in many cases, no machine is an island either.More capable software, improved network protocols, Ethernet, robots and other devices can form new and unexpected links between formerly standalone machines and production lines with modular components. And they're creating these ties, not just to improve product efficiency, but also to aid setup, inform operators, and update enterprise systems.
"We've been installing and automating robotic transfer units (RTUs) on overhead gantries or rails for about seven years, and it used to take a lot of engineering time to present 5–1,500 kg parts for aerospace, automotive and oil-rig applications to the six-axis robots and machining centers we work with," says David Flora, elecro-maintenance technician at system integrator Gosiger in Dayton, Ohio. "We often have one of Fanuc's RTUs serving eight to 12 machining centers, such as Okuma lathes, grinders and milling machines, but once we began using EtherNet/IP about four years ago to do the handshaking for loading and starting, it cut our implementation labor and time by 20–30% and made these lines much more efficient on average. EtherNet/IP and Fanuc's devices also saved us a lot of time on integrating sensing, vision components, cameras and infrared lighting."Flora explains that each machine still uses its own CNC program, interface and DeviceNet network protocol to make products, but during a typical handshake it also notifies the RTU that it's done with a part and needs unloading and loading, which tells the robot to get ready to work in the software-defined space they both share. These communications go from I/O blocks in the back of each machine to the RTU, function blocks and PLC controlling the line (Figure 1).
"Conversely, the robot also can upload CNC programs to the machines, tell them to perform certain operations, and then select the right binary-output program from their own lists," Flora explains. "Every job and solution is unique, but everybody wants more automation. So, our job is to make the RTUs and machine controls more compatible, and EtherNet/IP and our other protocols help us do it more simply and easily."
Brian Sides, technology director at Okuma America in Charlotte, N.C., adds, "Many users are beginning to realize they're not employing their machines up to full potential. They might believe a machine runs at 80% of maximum utilization, but if it's only running for one shift, that's really 20–30% of maximum utilization. Likewise, others want to improve maintenance quotas, but find it's hard to connect Ethernet to their machines and difficult to download and set up software programs. So many are moving to PC-based controls like our Intelligent Numerical Control (THINC). They also want a black box they can connect to all their legacy controls, so they recently used small PLCs with I/O modules. We responded by making this type of module standard in all our machines, so they can link to their legacy devices without having to add other components."
Though many machine connections occur between a few closely clustered devices, other links tie together components over much more lengthy production lines. For example, system integrator PeakLogix in Midlothian, Va., builds conveying and sorting systems for some of the largest U.S. medical supply distribution centers.
During the past five or six years, PeakLogix helped build conveyors at 15 distribution centers for one client, and is presently building two more. The typical conveying and sorting line usually has about eight to 10 different spurs and about six picking zones, which is another 100 ft conveyor with a bidirectional diverter. These zones can be on one to three levels (Figure 2). Lately, these material handling structures are integrating hundreds of proximity sensors, solenoids, limit switches, photo eyes, stack lights and horns into centralized PC-based controls via Ethernet, but retrieving all those signals didn't look easy at first."We had lots of small devices and sensors over a wide area, and we just couldn't bring them all back to where we wanted," says Matt Cummings, technical services director at PeakLogix. "However, we found that our PC-based Steeplechase VLC control software could use Phoenix Contact's bus couplers with IP addresses to localize I/O points in each zone on the conveyor, and then send back one Ethernet cable with multiple TCP/IP signals, instead of sending back wires from 20 sensors. We also learned that we could do the same with motor controls, contactors and protectors in our distributed panels. Besides saving thousands of feet of cable, wiring installations that used to take at least a month now take one or two weeks. I also found that our Value Line PC's Windows environment allowed me to run some Visual Basic code over an OPC connection back out to descriptive reference tags in our distributed controls, and email alerts and activate stack lights. And Windows also means we can connect and do remote diagnostics from anywhere using pcAnywhere or remote desktop software."
PeakLogix's users also wanted statistics on sorting performance by the conveyors in individual spurs, Cummings adds, but this level of detail wasn't possible before. "So we use the connections on our new network to show the daily load on the overall conveyor and on each spur," he says. "If one spur gets too busy, it will show up on their panel, and they can shift some of the load up or down the overall sorter for more efficient performance."