Conflex uses Beckhoff CX1020 Embedded PCs with TwinCAT, handling all PLC functions and motion control on a single device. Their CX1020s are directly connected to EtherCAT I/O.

The Modular CW and ServoFlex™ wrapping machines are tailored to the food, consumer goods, electronic media and printing industries, wrapping products that range from frozen foods, CDs and DVDs, to household products and toys. Joe Morrissey, Product Manager, sought control and network systems that would impart sufficient operation flexibility to the machines for customers in these diverse industries.

The old ServoFlex design used many intelligent drives for motion control. The required programming time for them, however, irritated customers. In a three-servo system, each axis had its own controller that had to be individually programmed because the drives weren’t equipped for Ethernet connectivity.

Adding or removing I/O was also something of a nuisance. Failure of even a single I/O point in the intelligent drive system meant the whole board had to be replaced.

In late 2005, Larry Koenigs, electrical engineer at Conflex, encountered Don Seicther of Beckhoff Automation. Koenigs and his team had chosen a new platform from a major automation and controls vendor. “It was an acceptable motion controller with PLC function, but it didn’t have all the programming and flexibility that we hoped and we accepted that we would put more time and effort into the controls design than was ideal. The call from Don arrived just before we planned to order our controllers.”

Koenigs switched to the DIN rail mounted Beckhoff CX1020 Embedded PC and TwinCAT IEC 6 1131-3 compliant automation and motion control software. “The control and software allowed us to create our ideal electrical controls system,” he said.

The ServoFlex™ line had a complete mechanical and electrical redesign that lets users program it themselves for multiple operations. An automated instructional feature teaches operators how to use the machine.

The ServoFlex machines now use the CX1020 with 1 GHz Intel® Celeron® M ULV processor and TwinCAT as the main control platform. It lets engineers handle all PLC functions and motion control on one device.

The Servo Flex is a four-axis system — one master axis with three slave axes. The horizontal form, fill, and seal wrapper delivers continuous motion at up to 100 ft of film per minute with an advanced reciprocating hot knife seal system. The machines have cradle-style powered film feed, which is easy to load and allows fast changeover.

Several programming libraries in TwinCAT were helpful. The prewritten Flying Saw code saved time and effort. On the Servo Flex, a vacuum conveyor holds the wrapper film and leads it to the sealing area that uses a reciprocating motion. The Flying Saw program handles the sealing motion of the knife moving back and forth on the machine. A pneumatic cylinder closes a sealing jaw while the cut is made. Built-in libraries for PID temperature control for the machine’s film heaters and superimposed move for print registration also save time in the packaging area.

EtherCAT ensures speeds match between the film-cutting knife and the incoming wrapper film. Some EtherCAT I/O terminals handle special latching functions for hardware interrupt. Latch input helps synchronize machine cutting and sealing operations to the printed film for a professional looking finished product.

The EL5101 EtherCAT Terminal interface directly connects incremental encoders with differential inputs (RS485). A 16-bit counter with a quadrature decoder and a 16-bit latch for the zero pulse can be read, set, or enabled. Incremental encoders with alarm outputs can be connected at the interface‘s status input. Interval measurement with a resolution of 500 ns is possible.

Beckhoff Automation
www.beckhoffautomation.com