BHP Steel is Australia’s largest manufacturer of steel and steel products. They have a number of manufacturing facilities throughout Australia, one of which is a steel mini-mill at Rooty Hill, a western suburb of Sydney.

The facility consists of a melt shop and a rolling mill that produces rolled bar products such as ‘Y’ and concrete reinforcing bar. The production process in the rolling mill involves reheating long square section billets to a specific rolling temperature and then passing it through a series of ever decreasing rolling stations at an ever increasing speed to keep mass flow constant. At the end of the process the bar is cut to length and bundled, ready for delivery.

The mill was originally constructed in the early 90’s and the control systems have remained basically unchanged from that time.

Low level control is carried out by Siemens PLCs communicating over an H1 Ethernet network. Operator control is available through workstations running Intellution’s The Fix HMI / SCADA product at three separate locations (or pulpits). In the original system all three locations communicated to the PLCs to obtain their data.

Production parameters are set by schedules created using a Microsoft Access database and loaded into the PLCs through software that communicates with the Fix tag database using the Application Programming Interface supplied by Intellution. These schedules contain the machine parameters required to manufacture a specific product.

Because of Y2K concerns, and a requirement to modernise the high level controls so that they could be adequately maintained, CSE Technology was contracted to upgrade the system to use current versions for all the software and make the required changes to keep the same functionality.

The original system architecture was changed to incorporate dual redundant SCADA servers for reliability and ease of maintenance. This required combining the three SCADA nodes into one, a process that was simplified by the very good tag naming conventions in the original system that resulted in just 5 tag name clashes in a total of about 3000 database tags.

A LAN was installed and the original Fix View nodes now obtain all their data from the centralised SCADA servers. This minimises the amount of communication to the PLC equipment and has the advantage that the alarm log can now be read ‘online’ rather than print a hard copy for distribution. Schedule updates can now be transferred over the LAN instead of by floppy disk.

The Fix security was implemented to give appropriate access to operators at each pulpit so that they have the same functionality as before the change and cannot interfere with other parts of the plant. The security system and some smart configuration also allow the Engineers’ Workstation to be used as a development tool or as a quick replacement for a damaged Pulpit computer. This gives an added level of redundancy that ensures minimum downtime.

The Access application was revised to work in the new environment. This required a substantial rewriting and testing of the system interfaces for the software.

The system was progressively tested on site during available scheduled down time by BHP staff. Interestingly, most of the faults found in the new system were inherent in the old system. The cutover period was used as an opportunity to correct these ‘legacy bugs’ so that now the system is the best that it has ever been.

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