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Article | May 31, 2003
Fieldbus shrinks bundler's controls, assembly time
A new fieldbus for EDL’s in-line shrink bundler reduces control cabinet size by 50% and reduces wiring time by 30%, while increasing flexibility.
When EDL Packaging Engineers upgraded its MSI 22-8 in-line shrink bundler with a fieldbus network inside the machine it was able to halve the size of the control cabinet which was a big issue with customers. The machine wraps trayed bottles or cans in shrink film.
“We needed to trim down our control cabinet” says Roger Steinfeldt EDL’s automation engineer. “Customers didn’t like having a big boxy control cabinet on the end of the machine.”
The solution involved switching from traditional wiring known as point-to-point wiring to a fieldbus. The fieldbus is a network within the machine that simplifies wiring of individual components ranging from sensors to motion controllers to human-machine interface.
EDL’s network which is based on ethernet uses fieldbus components known as bus couplers from Wago. Eliminating the PLC and the terminal blocks associated with traditional point-to-point wiring is what enabled EDL to dramatically reduce the size of its control cabinet scoring points with customers.
The fieldbus also makes it quicker to wire the machine during assembly. “Now we don’t have to run wires from a PLC to a terminal block and from the terminal block out to each device. We eliminate the whole terminal block right out of the picture.” Steinfeldt estimates wiring time has been reduced by 30%.
One of the bus couplers on the machine is what Wago calls its Programmable Field Controller (PFC). This PFC which controls the fieldbus has enough computing power to act as the controller for the entire packaging machine. In fact EDL did away with the machine’s traditional PLC letting the PFC do the work instead. That saved money: To upgrade the machine’s previous PLC to match the functionality provided by Wago EDL would have had to spend more than twice as much as it did for the Wago components Steinfeldt estimates.
Wago’s fieldbus technology is also more flexible when it comes to adding additional points of I/O which can be purchased in as little as groups of two and snapped onto the bus coupler.
The fieldbus also simplifies troubleshooting in the field for both EDL and its customers. “The age-old problem is the control box is on one side of the machine and the problem is on the other side” explains Steinfeldt. “By having the fieldbus bus coupler close to where you’re working on the machine you’re not jumping over conveyors and running to the other side to see whether an LED indicator is lit.” The fieldbus couplers rather than being housed inside the control cabinet are distributed throughout the machine and are much closer to the sensors and actuators to which they’re connected.
With the new fieldbus the price of the machine did not change according to EDL. If customers do require a full-fledged PLC EDL charges extra depending on the make and model of PLC requested. —DN
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