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* Application Software: This means a program that provides a specific function. For example, if you need statistical process control and reporting functions, then NWA (http://www.nwasoft.com) provides its Quality Analyst software. Blue Diamond Growers, Sacramento, Calif., uses Quality Analyst to acquire data from PLCs and a Wonderware HMI/SCADA system, perform statistical analyses, and make reports available to interested parties via its company intranet. No ERP is involved.
Iconics (http://www.iconics.com) offers ReportWorX.Net, which can produce the kinds of detailed reports that once required IT, MES, and ERP systems. ReportWorX uses .Net and XML technology, so it can provide web access, wireless communications, and interfaces to other .Net systems.
Many of the HMI/SCADA packages also provide connections to reach upward in the IT hierarchy. For example, InduSoft's (http://www.indusoft.com) Web Studio V 5.1 provides web-enabled SCADA and HMI systems that support .Net, Web Services, and XML. Any other modern HMI/SCADA system from Wonderware, Intellution, Iconics, or several others may provide the connection you need to reach IT software via Web Services.
With a little bit of programming experience and some of this application software, you can do wonders. "When historical data and report generation are concerned, we'll use an SQL-compliant report generation package, or write our own application using Visual Basic in Excel or Access," says Randy Geist, engineering manager at Technical Systems Inc. (http://www.TSIcontrols.com). "Data reduction and compaction are done in another SQL-compliant package." Who needs ERP?
* Historians: Every process control vendor has a historian package, which is simply a large database that stores everything that happens in real time. The most famous and long-lived is OSIsoft's PI package, which integrates with just about everything from 25-year-old legacy DCSs to the latest SAP NetWeaver.
Getting to ERP via a historian is a very popular method, it seems. "If our customer requests an ERP interface, we recommend OSI's RLink or a similar product," says systems integrator Phil Murray of Feedforward (http://www.feedforward.com). Mike Paulonis, technical associate at Eastman Chemical, Kingsport, Tenn., also uses RLink. "It is a much better choice in the long run to use a supported commercial product to make this connection," says Paulonis. "Eastman uses RLink, which provides a bidirectional connection between SAP and OSI's UDS universal data server."
Any of the other commercial historian packages can also provide an interface to IT software, because they all support XML, Web Services, SQL Server, and .Net.
Schwenezer says that OSI recently released PI-ICE, a server that provides PI with Web Services. "It was only released for six weeks in 2002, and sold nearly 1,800 seats," says Schwenezer, an indication that users are jumping on the Web Services bandwagon.
If you are having any doubts about ERP, this might be an excellent place to stop. "The ERP market is questionable," says Murray. "Scheduled 'go live' data are delayed by years. Plant personnel generally believe that they can manufacture and ship quality product on time without intervention, and they resist installation because of perceived misery with ERP."
It's quite possible you can obtain ERP-like reports without the agony, just by using suitable application software and a historian. If not, there are always frameworks systems.
Frameworks are an "overarching architecture or framework to ease integration of plant floor and enterprise systems," we reported in a January feature "Framework Wars" [CONTROL"Jan. '03, p50]. "All of these frameworks use industry standards such as OPC, DNA for Manufacturing, and .Net." We also reported that many of you regard all this with great skepticism, and suspect that it is yet another way that process control vendors are trying to lock you into their proprietary boxes.
Chris Boothroyd, product manager at Honeywell, says such intervening software is necessary. "If production-level software and ERP software both support XML, then integration is simplified," says Boothroyd. "But unless both systems use exactly the same XML schema in exactly the same way, then something must still be used to interpret the messages between the two systems."
It is important to note here that XML schema, as defined in a DTD, is what makes the whole system work. When using XML to send data between two systems, both systems--by definition--must use the same schema in exactly the same way. One system tells the other which DTD is being used to encode the data, so the receiving system can use the same DTD to extract the data. There can be no mistakes. This is not a limitation of XML; instead, it may be its most redeeming feature, because the DTDs are public documents. They cannot be made proprietary.
Of course, we have not quite reached that stage yet, because XML schema are still developing. That means we might still need frameworks systems.
"An additional layer of software will sit between the control system and the ERP system," adds Boothroyd. "This might be as simple as a process historian or as complex as a full-blown MES. This layer of software becomes the focal point for ERP integration."
ControlGlobal.com is exclusively dedicated to the global process automation market. We report on developing industry trends, illustrate successful industry applications, and update the basic skills and knowledge base that provide the profession's foundation.