The
goal of ramping up production of rolled steel at BHP's Wollongong
plant is made easier by moving their mill control systems to a real-time
UNIX platform.
BHP Steel,
Sheet and Coil, a division of the massive BHP multinational company,
produces over 700,000 tons of rolled steel annually at their award
winning close-coupled cold pickle mill in Wollongong, Australia.
Because of demand and market forces, it was decided to increase the
capacity to over 1 million tons per annum by the incorporation of
a revolutionary multi-headed coiler at the end of the line. To do
this however, the process computer system responsible for control
of the mill needed to be upgraded. Since this system, an aging and
obsolete DEC PDP/11 84 was at the top of the line for real-time performance,
BHP decided to evaluate real-time systems currently available based
on their demanding criteria.
After discussions with MODCOMP and Australian representative Kirkby
Associates, it was decided that REAL/STAR series of processors, which
use MODCOMP's POSIX compliant real-time UNIX, REAL/IX would meet their
needs.
Don Farrar, Senior Supervising Electrical Engineer of BHP Engineering,
states, "We needed not only a computer system with real-time
performance, but also the confidence that the job we needed done could
be done in time for the implementation of our mill upgrade scheduled
for November 1995. At the same time, we needed to preserve our investment
in software production algorithms designed and implemented over several
years. MODCOMP offered the real-time performance we needed, the porting
tools to successfully migrate our legacy code from a proprietary environment
with a minimum of recoding and the added advantage of a fully Open
Systems platform for our plant.
"Furthermore, the MODCOMP system also offered the ability both
to connect our old PDP systems running our Pulpit display systems
using DECnet, and also communicate with newer systems using TCP/IP.
It fitted our needs almost exactly."
The heart of the new MODCOMP system is a powerful RISC processor housed
on a VME card. Incorporated in the system are two Ethernet connections,
serial I/O and the plant I/O controller. This connects the Computer
Products, Inc. (CPI) to the MODCOMP system.
The control system was planned to be installed during first phase
of the coiler upgrade program. Work commenced on the project in December
1994, after the delivery of the first REAL/STAR system.
And the implementation of the new system? Although the change from
a proprietary RSX-11M environment to UNIX was a little strange at
first, it was found that there were plenty of people in-house with
familiarity of UNIX who could be called on for advice. The older FORTRAN
code was easily compiled to run under REAL/IX, with only proprietary
system calls needing to be replaced to take advantage of the real-time
POSIX libraries. The total project involved two software engineers
for a total of six months, including the learning curve associated
with the migration to a new operating system.
The connection to the existing plant I/O was as simple as moving a
cable from the old system to the MODCOMP system. Testing was then
possible during a planned mill shutdown period, with a fallback position
to the old system should any insurmountable problems be found. Fortunately,
this did not occur and BHP had the confidence to put the MODCOMP systems
running the live plant on schedule, in May 1995.
Since the changeover date, performance improvements have been dramatic.
The system loop cycle time has been reduced from approximately 40ms
to 3.75ms, and overall system performance has improved approximately
9-fold. The installation of the MODCOMP system with the improved performance
also affected the plant production, with an operating record of 21,000
tons per week being reached in September 1995.
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