|  Spring 1999: In
an upgrade to their Titusville, PA lumber processing yard and
grading station, Weyerhaeuser decided to install technology that
would pay immediate dividends as well as give them a foundation
to build upon for future needs. Ultimately, they wanted to install
a system that would help them stay at the forefront of their industry
for many years to come.
Understanding that streamlining was an important step in staying
ahead of the competition, Weyerhaeuser embarked on a review of
their process that indicated their grading operation was a choke
point in their overall system. Improving the capacity through
the lumber grading station was the most logical way to increase
overall productivity and profitability of the entire system. |
| Weyerhaeuser turned to
a local systems integrator to recommend control and data
acquisition products, as well as an overall system approach to
improve the grading station. Given the needs and goals of the
Weyerhaeuser system, the integrator designed and implemented an open architecture
control system utilizing a SoftPLC in Tealware™ PLC, coupled
with RSVIEW32 as the operator interface.
The control system was designed to provide maximum reliability,
ease of maintenance, and connectivity to the plant's data collection
system. At the heart of the system is a
SoftPLC In Tealware controller from SoftPLC Corporation, which provides control and
tracking information for all lumber that passes through the system.
This controller is a PC/PLC hybrid that offers the user the power
and flexibility of a PC while retaining the familiar feel and
reliability of a PLC.
Three racks of local SoftPLC In Tealware I/O are used for control
of the majority of discrete field devices in the system. In addition
to the local I/O, the SoftPLC controls a DeviceNet network. DeviceNet was selected for communication
to some specialty I/O included in the system. (One unique feature
of SoftPLC In Tealware is a mounting base that includes not only
slots for the Tealware CPU and I/O, but also up to 5 PC/104 add-on
cards, such as the DeviceNet card used in this application.) |
"When
implementing leading edge technologies in facilities that require
98%+ uptime, 24 hours a day, 7 days a week, it is important to ensure
the reliability of the system, and thus the profitability of the customer."
Connectivity requirements
of the system indicated that a PC based solution might be the ideal
design while recognizing that reliability and vendor reputation was
key. "SoftPLC was chosen because of its high MTBF,
flexibility, speed, and use of ethernet communication"
-- VP of integrator
|
"DeviceNet was used for its diagnostic capabilities,"
explains the project engineer. "Replacing
the standard limit switch/whisker combination for measurement are DeviceNet
photo eye units, which were chosen because of their ability to judge when
they are becoming dirty. This is important as they are used as part of the
board quality calculation. A non-functioning photo eye could cost the customer
thousands of dollars." DeviceNet was also utilized for communication
to a Bar Code Scanner and an encoder used to provide system timing as well
as measurement calculations.
Operator interface stations are located throughout the plant. These O/Is provide
the Weyerhaeuser employees access to control the operation and enter data
not already automatically processed.
A key feature of SoftPLC that was utilized for the system was the embedded
real-time web server. This allows the control system developer to place HTML
documents on-board the SoftPLC CPU, which can access real time information
directly from the SoftPLC data table, and embed the live data into the web
page without adding communications overhead. The on-board "web site" can then
be accessed by anyone given clearance through any web browser on the intranet.
The project manager for Weyerhaeuser explains "We
chose the critical information we wanted to see and put it on a web page.
Now any leader on the plant's network can see the critical metrics of the
grade station - in real time, with no special software required!"
| Another item of primary importance to Weyerhaeuser
was the retention of their data collection system. The new automated
grading system provides Weyerhaeuser a means to track inventory
into the grading system without any manual translation of data.
Previously, this task was accomplished through the use of proprietary
data collection software, which while functional, afforded a more
complicated means of connection to MS Access than offered by the
data collection capabilities within the new operator interface.
Bar-code scanners were added to input pertinent data to the system
prior to any processing in the plant. |
"RSVIEW was used to perform
the data collection -- and communications to SoftPLC over ethernet
were easily established using standard available drivers from A-B"
"Bar-coding permitted us to enter the data
one time and maintain visibility of the material through all of
our value added steps. Bar coding also removed multiple opportunities
for error, which existed in the manual ticketing system. Further,
it has reduced manual reconciliation." |
Overall, by combining products from multiple vendors -- SoftPLC In Tealware CPU
and I/O, DeviceNet I/O, a web browser, and RSVIEW32 --Weyerhaeuser has been given
the stability of a traditional grading control system while providing immediate
improvements and a platform on which to build in the future. Most importantly,
the company effectively doubled the throughput of the grading station, the original
goal of the project.
"The improved throughput of the grade station reduces
the need to use the air dry yard as a buffer. Another way to say that is,
the technology solution allowed us to reduce inventory. We now recognize inventory
as an indication of bad information."
UPDATE: Due to the success of this project, and Weyerhaeuser's satisfaction with SoftPLC, the plant
has since retrofitted their dry kilns with SoftPLC in Tealware controls as well.
|
