March 2005 - The Logging and Sawmilling Journal
New Developments in Process Monitoring and Control
Standardization of data exchange methods in the sawmill make real-time production status available to decision-makers.
Today’s machine centre optimizers epitomize this scenario: being very capable of making good decisions in isolation, but less capable of optimal decisions when other factors (such as log diet, customer order file, tool wear or malfunction, and conveyor congestion) are considered. In recent years, some machine vendors have offered machine-to-machine communications protocols, but these products have been single-vendor solutions that may not reflect the true multi-vendor environment of the modern sawmill. What the customer requires is agreement between these vendors on a common data-sharing standard. This co-operation is not novel, as several other industrial sectors have achieved data-sharing standards, given similar circumstances.
The pulp & and paper, chemical, and automotive industries each use standard data-sharing methods extensively. This universal methodology to connect, and exchange data with plug-and-play simplicity is “OLE (Object Linking and Embedding) for Process Control” (OPC) or, commonly termed “OPC technology.” In the forest products industry, specifically, consulting firms have addressed the problem by creating custom data access methods for each machine centre, then providing process data servers with connectivity to the management information systems.
Universal Data Access
In 1996, the original OPC task force released its first specification. Today there are over 300 member companies of the OPC Foundation worldwide, including Fieldbus Foundation, Ford Motor Co, Honeywell Inc, Microsoft, National Instruments, Rockwell Automation, Shell Global Solutions, Siemens AG, Weyerhaeuser, and Wind River. The widespread adoption of vendor-independent OPC tag-based standards has bridged the data accessibility gap between devices and machines.
A wave of HMI (Human Machine Interface), ERP (Enterprise Resource Planning), and SCADA (Supervisory Control and Data Acquisition) systems now utilize OPC standards to access real-time and historical data to provide the information needed for process monitoring and control in the mill. Phil Milliman, manufacturing systems consultant at Weyerhaeuser, observes that, “Weyerhaeuser Company is actively using an increasing number of OPC interfaces in Pulp, OSB, and Wood Products.” As an industry, we should ride that wave.
Milliman, acknowledging Weyerhaeuser’s commitment to OPC technology: “Weyerhaeuser is actively using OPC interfaces with many manufacturing processes and in some cases have built custom, interim OPC interfaces for devices such as moisture meters, until such time as the suppliers provide their own OPC interfaces. OPC is quickly becoming the preferred interface for softwood lumber integrated systems.” In a joint effort with the Scierie Leduc mill in Quebec, Forintek has developed an OPC server for a kiln controller that provides access to all measurements in their kiln as well as controller set points. Coupled with the real-time PI database historian from OSIsoft, the prototype server has been running for two years now, demonstrating the possibility of access to all kiln controller data.
Standard Data Access
Criteria for the project were low deployment cost, modularity, flexibility, configurability, and payback. In early 2003, a mill data server was installed and began collecting PLC data, making real-time and trend information available from anywhere within the mill, with an Internet browser. Leveraging on the new ability of everyone to view the history of disabled j-hooks and lack of spare bins throughout the shift, for example, it was not long before these nuisance issues were resolved. By year-end Cliff Tuttle, technical director at Pope & Talbot, observed that “usage of PLC data alone has reduced mill costs by about $120,000 on an investment of about $20,000 since tthe system was installed last spring.” Rick Haffner, mill manager at Midway, exclaimed that “this is a great tool for maintenance and superintendent staff.”
In the meantime Porter Engineering provided optimizer upgrades to two primary breakdown optimizers, providing offering OPC tag access to optimizer summary data for the first time in January 2004. In this groundbreaking effort, Porter Engineering provided a realistic tag-list for primary breakdown optimizers. It is here, at the tag-list level, where OPC technology becomes customized for the use by the sawmilling industry, built on top of industrial OPC data access standards. Vendor-independent tag-lists specific to machine centre types are the key to plug-and-play optimizer data exchange.
The project at Midway has been so successful that the company is planning a similar roll-out in another mill, this time including an OPC tag upgrade to a bucking optimizer from Porter Engineering. Having demonstrated the viability suitability of OPC technology to sawmill conditions, more equipment vendors are actively investigating this method of exposing their optimizer data. Yvon Hubert, general manager of Comact Optimisation Inc, indicated their readiness to deliver OPC tag upgrades for their optimizers, but nobody has ordered OPC tags to date. Daniel Éthier, vice-president of Autolog Inc summarized his company’s conclusions about OPC technology: “At Autolog Inc, we strongly believe in the OPC standard, but in the last year we realized the .NET technology can make OPC a more complete data communication system approach.
By introducing their new .NET technology, Microsoft has enabled a plethora of advancements in many areas such as web services, data source independence, easy exchange of data and many more. “Autolog Inc has fully embraced the .NET framework, especially the XML format to exchange various information amongst its systems both internally and to expose data to outside sources. By using XML as a way to exchange data, we immediately gain many benefits such as easy-to-read-by-humans tag-based documents, the ability to push data through firewalls on the network, a version-independent way to transfer buffers, an industry standard way to communicate with outside sources, and more.
By using OPC, XML information can be transmitted using a common approach across the various nodes which make up the control system: PLCs, Optimizers, Control computer, and PCs.” Consulting firm Valley West Controls Ltd, being an early entrant to the mill data server business, spans both worlds of custom machine centre access and OPC data access. Rob McLean, of Valley West, observed that the job of collecting summary optimizer data is faster when optimizers are already equipped with OPC data access. The mere availability of real-time and historical data, however, does not by itself guarantee any benefits. Eric Jennings, senior systems analyst at Hinz Automation Inc, and responsible for the mill data server installation at Midway, observed that mill information systems require a well-designed plan to be effective, a plan that specifies different levels of reporting. For example, production or maintenance managers require different types of reports and information than do mill managers or people from head office.
The Future is Now
For more information about the Data Communications Standards project, contact Ron Niessen at Forintek Canada Corp. Tel: 604-224-3221; e-mail: firstname.lastname@example.org. For more information about the OPC Foundation, go to www.opcfoundation.org.
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