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Article | December 12, 2012
A new approach to conveyors
Different products can be conveyed on a single line and moved in different directions, while an operator has complete control over the speed and direction of movement of the conveyed food products by implementing control commands virtually in real-time.
21 servo axes
tna Australia Pty Ltd., based in Silverwater, Australia, is one of the world’s leading manufacturers of turnkey, integrated packaging and processing solutions for the food industry. The tna horizontal and vibrating conveyors distribute and transport products such as snacks, confections, nuts, pasta, fresh produce or pet foods and feed them to a packaging system. Their most recent horizontal conveyor system, the tna roflo HM 3, is an innovative solution for the transport and distribution of food products.
“It was specially developed with a view toward simple integration in upstream or downstream seasoning, weighing and packaging modules and enables the development of customer-specific solutions,” explains Kerryn Ball of tna. More strikingly, it allows “different products to be conveyed at the same time on a single line and moved in different directions,” Ball says.
This new conveyor gives the operator complete control over the speed and direction of movement of the conveyed food products by implementing control commands virtually in real-time. With a view to performance optimization, tna’s aim in developing the conveyor was to implement a distributed control system with real-time Ethernet as the basis for communication.
“Prior to the start, tna had considered a range of communication options. Ultimately, EtherCat was the only system that is proven to work efficiently on standard hardware without having to install a processor board especially for the communication,” Ball stresses.
“Since EtherCat is an open standard protocol, we were able to develop our own EtherCat master for real-time communication with the horizontal distribution system. The openness of the EtherCat platform also gives us the option to use devices from different vendors. That offers both us and our customers valuable flexibility,” says Ball.
21 servo axes
tna has now installed EtherCat into all non-standalone tna roflo HM 3 systems worldwide. Currently, the most extensive system of this type is located in France, where 21 servo axes for three production lines are controlled by just one computer. A single communication network can be used for several tna roflo HM 3 systems.
The connection to the field level takes place via the EK1100 EtherCat Coupler. Digital inputs such as level sensors and all universal inputs are connected via standard input terminals. Air-operated doors, warning lamps, etc. are connected to the digital output terminals. The EK1122 branch terminals increase the topology options of the EtherCat network in the case of larger systems for which a star topology is suitable.
In the French installation, 21 tna roflo HM modules make up a distribution system that is tailored to the needs of the customer’s application. A single tna “switcheroo” or “lifteroo” feed line—a mechanism that separates, tilts and turns the tna roflo HM pans—is able to distribute three different products from the processing line to the waiting packaging machines. This innovative function changes the way in which processing lines are interconnected and enables the simultaneous movement of products in several directions on a single packaging line.
“Previously, we needed three conventional feed lines for this—with the corresponding costs and space requirements. With the EtherCat-based controller, the 21 servo axes distributed throughout the entire factory are controlled by just one powerful computer,” says Ball.
“Thanks to EtherCat we can build and test the tna roflo HM modules at our production site. All cables are located in the roflo HM modules; in addition, information is exchanged over the network so that no ‘spaghetti cabling’ is created and the system can be designed very simply,” he says, noting that EtherCat offered the foundation for real-time communication in the machine modules.
In addition, the sytems openness enabled the development of a tna-designed, proprietary EtherCat master that helped to shorten installation time thanks to a simple network structure and reduced cabling work.
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