Integrated SCADA and soft logic increases machine productivity

01 April 2006

For large machines that have a variety of controlled peripheral components, a ‘single point of administration’ eliminates many problems.

An information and control system for plastic part production at toothbrush manufacturer Braun/Gillette in Germany now offers universal transparency of the production data, thanks to the work of Project-Manager Dipl.-Computer Engineer Gerhard Dittmaier and his PC-based solution. The application, which is running at the company’s plant in Marktheidenfeld, is based on the real-time soft logic control system STRATON and the SCADA/HMI process control system zenOn. Both are from Copa-Data and they are tightly integrated with one another.

Mr. Dittmaier’s idea of ‘ProCICS’— Production Cell Information and Control System—was to improve productivity and simultaneously reduce costs on his company’s plastic injection moulding machines. His project team analysed the system requirements, taking into account the experiences of all production co-workers responsible for the day-to-day functioning of the injection-moulding work cell.

The team decided that all external equipment on the injection-moulding machine should be integrated into the main control system. Until now, the external equipment, such as the Reis part removal robots, feed units, and temperature control units, were considered to be ‘peripheral’ and had been excluded from the control.

This decision would give ‘immense operational advantages,’ the team decided, through more efficient
signalling of error and failure messages. An appropriate data transfer to the central sites was necessary to realise this goal, and furthermore, ‘easy to use’ software was needed to gather and present the information in a meaningful way to the operators. This would allow them to quickly react to problems, and by their manual intervention could dramatically minimise production defects.

Single point of administration The team decided that the most important requirements to be fulfilled by the control system were modular upgradeability, openness for manufacturer independent expansion, and machine independence. This would ensure the integration in a central management system or production
control from various workplaces. As Mr. Dittmaier likes to put it, ‘With ProCICS, we accomplish a single point of administration in our factory.’

Faced with these requirements, those involved with the project realised that every injection machine work cell on the factory floor was comprised of several different and independent devices with various interfaces. There were, for example, Modbus interfaces for the feed units, Profibus interfaces for the temperature control units, and serial interfaces with manufacturer-specific protocols on the part removal robots and in the injection moulding machine itself. Added to this, there were I/O interfaces on older devices.

This variety of interfaces and the proprietary protocols made direct communication—and interaction—
between the individual devices an impossibility. They were, in effect, isolated from one another. So if one of
the ‘peripheral’ components malfunctioned or dropped out, unless the operator was nearby and noticed it
when it happened, no correction to the process occurred. This resulted in production defects and, at worst, the plant could come to a standstill.

To address the problem, each injection moulding machine was fitted with an embedded PC that has as an operator interface a touch screen from Lauer. The hardware was equipped with two network interfaces so that the entire production cell could be ‘sealed off’ from the outside—from the network point of view—and thus unauthorised access to internal data could be prevented. Through the second network interface the work cell obtains a unique IP address in the corporate internal network, in order to be able to, for example, retrieve data from the central control room.

Braun worked with the system integrator Prozesstechnik Kropf who proposed Copa-Data’s product suite
zenOn/STRATON. It was the soft logic part of the package, the STRATON software, that made it possible to
communicate with, and control the peripheral components.

STRATON, integrated with zenOn, is an IEC 61131-3-based Soft-PLC package that has over 100 communication drivers at its disposal. Modbus, Profibus, or serial protocols are available as driver interfaces and therefore only have to be configured to be used.

As always, there was one exception to the communication drivers. None existed for the Reis part drawing robot, which is used to extract finished parts from the machine. However, a suitable driver was developed in short time by Prozesstechnik Kropf in collaboration with Copa-Data. With the addition of the Reis robot driver, it is now possible to automatically generate error messages from all components involved in the
production process, and to continually monitor the individual process parameters.

Old and new, in parallel operation
Since ProCICS was an entirely new control engineering and information handling venture for Mr. Dittmaier and his team, they decided it would be prudent to go slowly into the application, and make sure that if there were any errors, the old system would be available as back up. That way information and production would not be lost.

To this end, they developed a special multiplexer for the application. The multiplexer reads data from the injection moulding machine and, via serial interface, simultaneously sends the data to the new information system ProCICS as well as the previously connected Production Data Collection System (PDC System).

The newly developed ProCICS solution acts transparently for the PDC System. With the integrated zenOn/STRATON solution, data from the various peripheral machines not only can be extracted, but also logically combined with each other. Yet to the user the familiar development environment is still available, which is a major advantage. Engineering times can be shortened and errors minimised.

Through data combination it is possible for the plant operators to be more actively engaged in the process. Before, production failures would appear when changes in the process temperature went unnoticed. With the new system an error message is immediately generated through an alarm management interface and an SMS message is transmitted to control personnel’s mobile telephones, who can take immediate corrective action.

Should the error not be removed within a specified time period, the process is automatically stopped, which drastically reduces errors and scrap material. With production volumes in excess of one billion parts per year, there is understandably a huge cost saving potential in saving raw material.

System expansion already in the schedule Mr. Dittmaier says the pilot phase of the project—outfitting the first injection moulding machine work cell with the ProCICs zenOn/STRATON system—has been successfully completed, and that similar upgrades are planned for two additional systems. The next two work cells, in fact, have more complex environments, which will further test the system. He thinks that potentially, two-thirds of all moulding machines in the factory may be equipped with this type of SCADA, HMI,
and soft logic system, creating a ‘single point of administration’ for each one of them.

Mr. Dittmaier says Braun is considering the use of other zenOn features such as the Report Generator, data recording in the Chronological Event List (CEL), the Industrial Performance Analyser, and others.

zenOn has the ability to write all data in a database over a single SQL Driver. Since this is a read-and-write driver the data can be accessed by varying applications at any time. The communication takes place over ODBC (Open Data Base Connectivity). Thus zenOn can connect with management systems such as ERP (Enterprise Resource Planning).

Integrating soft logic with SCADA
One of the features of zenOn version 6 is that if offers, for the first time, an integrated soft-PLC package called STRATON. STRATON is based on the IEC61131-3 programming standard. It offers all the features of a modern PLC workbench such as the five standard programming languages, SFC, FBD, LD, ST, and IL, as well as extensive function libraries and help files in German, English, and French. Modern software design
permits quick compilation and enables an extensive ‘onlinechange’ functionality. Modified programs can be reloaded without process delays.

Integrating STRATON with zenOn eliminates double-data management and the associated error vulnerability that comes when two standalone software packages share the same configuration data. Integration of the two packages means there are no more time-consuming import/export processes for the variables; visualisation and control are combined into one package. Through ‘intelligent integration’ both parts yield the advantage of consistent data management. An applied variable in zenOn is also available in STRATON and vice versa. The creation from visualisation and control projects with a single data source is possible. That minimises error sources and saves engineering time and consequently costs.

Copa-Data says it developed this integrated solution without losing its openness to other controls. The common data storage is made possible through the documented and open database interface. This is the same foundation for the integration of workbenches and programmer environments of PLC or bus systems from other manufacturers.

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