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Are the people in accounting making you connect your plant floor equipment to their information technology (IT) systems? Does the CEO of your company actually believe all that plant-floor-to-top-floor hoopla? Do you want to connect your control system to process optimization software operating in a server 6,000 miles away?
In all these cases, you have to connect your PLC, PC, or DCS real-time control system to the world of transactions, databases, communications, and accounting. What's more, because typical IT people cannot possibly understand what you do (and are probably incapable of helping you anyway), you are going to have to learn what they do and make the connection yourself.
Fortunately, that's not much of a problem. Any engineer who understands feedforward control and relay ladder logic should be able to understand the elements of IT interfacing, including using XML and Web Services. "It is easier to teach an instrument and control engineer about computer networks than the other way around," says Ian Verhappen, director, ICE-Pros, Fort McMurray, Alberta.
Rise Above the Cloud
Interface technology is not that hard to understand, even if vendors, instructors, and magazine editors insist on making it seem that way. Most of us can relate to this comment by Don Erb, manager of planning and information at Ciba Specialty Chemicals, McIntosh, Ala.: "The technical terminology that is discussed at seminars and vendor presentations usually means little to me without further elaboration. It seems that when you attend a presentation, the presenters assume you already know what they are talking about."
Michael Larocca, senior process control engineering specialist at Solutia, Sauget, Ill., says he doesn't understand it all, either. "I know enough to know that a typical process control or automation engineer doesn't have to learn the intricacies of it to accomplish what he needs to get done," he says.
We've taken all that to heart here. We'll explain just enough so that you can deal with IT people in their language. However, please bear in mind that this is some serious stuff. As Pat Kennedy, president of OSIsoft (http://www.osisoft.com) puts it, "It is a total rethink--almost as big as the object rethink of the 1970s." In other words, XML and Web Services are about to revolutionize our industry, so you should get familiar with the terminology.
Figure 1: Get Through the Cloud
Plant-floor control systems can reach ERP and other information technology (IT) software in several ways including do-it-yourself connections using OPC and Visual Basic; broker software, such as process historians and frameworks systems; or by adopting the .Net architecture.
Let's start with the infamous Internet "cloud." You've seen this on diagrams. The Internet (or any network for that matter) is portrayed as a cloud (Figure 1), because you don't really care how you get to the ERP or IT system. You can connect through the "cloud" via Ethernet, Internet, intranet, wireless, hardwired connections, or combinations thereof.
Your control system world, on the other hand, exists in a clearly defined and protected space. It has its own networks, such as fieldbuses and device buses, that connect field instrumentation and control elements to workstations, control modules, HMIs, and similar equipment. It is safe, secure, and understandable, and most of it is hardwired. No one can get into this system from the outside unless you let them. No clouds here. You know where all the links are.
Now you have to connect this secure system to the outside, cloudy world, to IT systems such as supply chain management (SCM), planning, scheduling, modeling, ERP, MRP, WMS, CRM, and a host of other software described by three-letter acronyms (TLAs).
It's important to realize that it doesn't matter where these IT systems are located. They can be in the next room or around the world. And even if they are in the next room today, they might be on a server 6,000 miles away tomorrow. Just assume that all connections to IT go through the cloud, and don't worry about the physical connection.
Go Inside IT
IT systems, such as ERP or SCM, run on PCs, workstations, midrange computers, and mainframes. They run the gamut from UNIX to Microsoft operating systems, and from Sun to IBM processors.
In general, IT systems do not talk to your control system; instead, you talk to them. Your system supplies what they want when they want it, and it is usually a one-way street. As Jim Loar explains, it's because your system is real time and ERP is transactional.
"One problem in the integration is making the connection between two opposing philosophies and organizational goals," says Loar, engineering group leader at Ciba Specialty Chemicals, Newport, Del. "On the process control side, the goal is 100% uptime, 24/7, real-time, get the pounds out the door, and don't blow up the plant. On the other hand, the ERP side is defined transactions at discrete times, no activity during month-end close, centralized control, and financial accountability."
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.