New controls increase labeler's flexibility

Since 1989, Nutek has been developing and manufacturing customer-specific systems for printed circuit boards (PCBs) for the electronics industry. The company has always competed against strong national and international companies. But now it found itself facing a dilemma internally.

For its new production prototype of a PCB labeling machine, Nutek decided to use a PC-based controller from Beckhoff Automation. The bar-code labeler is just one part of a larger system product line used for creating PCBs. The systems currently supplied by Nutek consist of feed and discharge machines, inspection and connection conveyor belts, storage buffers, vertical buffers, traversing equipment, rotary conveyors and further system components. The traditional programmable logic controller (PLC) had reached its capacity due to the exacting requirements of product tracking and batch monitoring.

In addition to developing and building PCB handling systems for the electronics industry, Nutek also acts as an OEM on soldering systems under license from the Japanese company Tamura Corp. The company employs more than 500 staff members in development centers, production facilities and sales offices on six continents. Among its customers are the world market leaders for electronics production, such as Seagate, Sony, Philips, Hewlett-Packard and Motorola.

To rectify its problem, Nutek uses a new control concept that enables the company to achieve its ambitious goal of labeling every single PCB with correct labels at a high speed, using appropriate product tracking and batch monitoring functions.

Right from the start, it was clear that a flexible bar-code labeling system would require PC-based control that supports both PLC and numerical controller (NC) functions. The programming language had to be simple, since the Ladder Diagram (LD) programming language is a requirement in the South Asian market, which is dominated by Japanese PLC manufacturers. Since the control solution from Beckhoff meets these requirements, Nutek started using Beckhoff products. Nutek's efforts were supported by TDS Technology Pte Ltd., the sole Beckhoff agency in Singapore.

The crucial factor for Nutek was the integration of PLC and motion control within a single package. Further advantages are the standardized development environment based on IEC 61131-3, the comprehensive positioning and axis control, the diagnostic functions and the flexible data interfaces. Moreover, the use of Beckhoff's TwinCAT ADS interface enables communication between the bar-code labeling software and the PC control. The interface is a published open protocol based on TCP/IP, which is used for the software components, such as human/machine interface (HMI) and PLC, for communication both inside a single PC and from one PC to another. It is capable of riding on top of networks such as Ethernet, DeviceNet and Profibus and can be used for data collection, programming and configuration.

The control solution of the bar-code labeler is based on an industrial PC from Beckhoff, the TwinCAT and communication with the Beckhoff bus terminals via the Lightbus system.

Nutek has implemented bar-code labeling via three real axes?the XY axes and the Z axis–for attaching the labels. The serial communication library of TwinCAT is used for the communication between the bar-code printer and the PC control. The labels are attached to the PCBs at a speed of four labels per 12 seconds. For simplified operation, the machine positions can be taken up in the "teach and store" mode. The flexible system can integrate different bar-code printers; if a bar-code label has to be changed, the user can generate it on the same PC.

While programming within the Ladder Diagram is still a de-facto standard in Southeast Asia, Nutek engineers have mastered the development language for the bar-code labeling machine. Structured text, function block diagrams and sequential function charts are used during development. Nutek technicians prefer programming languages based on IEC 61131-3. The visualization system is developed with Visual Basic.

The option of simple remote maintenance is an advantage for Nutek. Data protocols, statistical analysis and intranet integration can be realized within a single system. The software poses no limits on increases in speed. The optimization of the mechanics and the drive systems will lead to further increases in performance.

More information is available:

PC-based controller: Beckhoff Automation LLC, 952/890-0000. www.beckhoff.com Circle No. 244.