Cover story: Integrating Disparate Control Systems
It’s love, says one popular song, that keeps us together. But when it comes to the manufacturing environment today, it’s more likely protocols, networks, and standards that are the bonds keeping us connected and communicating. And those tools are growing and thriving, linking our industrial operations together in new and useful ways and boosting manufacturing efficiency as never before.
Not too long ago, the plant floor was characterized by islands of automation—components, machines, and systems operating independently of each other and separately from management and other functions. Processes were slower and often difficult to optimize, and data for measuring performance, scheduling maintenance, and determining profitability were difficult, if not impossible, to obtain.
So what has happened to enable the connectivity that industry enjoys today? “A number of technology advancements have brought us to an automation and manufacturing world that is completely different from even 10 years ago,” said Joey Stubbs, PE, PMP, North American representative, EtherCAT Technology Group. “In fact, technology today is available to overcome most any networking barrier. You can install an EtherCAT-enabled DIN-rail mounted PC, for instance, that is able to ‘talk’ several other protocols. Although it might not be the most efficient system, or even the most cost-effective, it would be possible.”
As technology continues to evolve so dramatically and at a record pace—and is especially evident in consumer electronics—so have the expectations of suppliers and end-users for industrial automation, added Thomas J. Burke, OPC Foundation president and executive director. “The economy, today, and everything related— from building automation, security, and the concept of the smart grid—is driving the need for open industrial systems that span all domains and provide true information integration.”
Considering what, why, and how
Indeed, there are many good reasons to connect disparate manufacturing systems today, and even more ways to do it. Modern manufacturing uses diverse machinery and applies a variety of processes that—if industry is going to compete on the global level it has to today—must communicate with each other as well as compile and exchange information among all plant operations. Whether it be the automated ordering and just-in-time manufacturing of the automotive industry or the data tracking and tracing needed for batch processing in the pharma and semiconductor industries, communication has become a mainstay to keeping production systems operating optimally.
However connectivity or integration is accomplished, efficient movement of data means exchanging only information that is needed. Systems that minimize the need for multiple expensive software packages or cut the cost of hardware make for better process control, better products, and greater profitability. The methods used should share three common goals, suggested Stubbs. Systems should be connected so that they:
• Move data efficiently, such as through timely data transfer as with real time control systems;
• Lower costs with respect to managing the software that translates data or the hardware that facilitates the translation; and
• Operate with a low overhead without sacrificing large amounts of CPU power to perform translations, especially when that power could be better spent for actual production or process control.
Today’s systems go a long way toward doing just that. Bridges that link unlike components and devices can be created within one plant level and between plant levels as well. According to Corey McAtee, technical marketing manager, Beckhoff Automation, industrial automation and control operates over three distinct islands or layers—machine, process, and factory:
1. Machine level control architectures include safety and functionalities such as PLC, digital motion, and condition monitoring that traditionally were separate, but are now being brought together. Thanks to a high adoption rate of open standards and technologies by multiple vendors, these tiny islands are more readily bridged as fieldbus networks, such as EtherCAT, lend themselves to doing many functions across the machine controller.
2. Process-side islands. Few machines operate alone; they are part of a line or a process. “A manufacturer might buy three machines from three vendors,” said McAtee, “all of which must work together and talk to each other. Standards like OPC-UA (unified architecture) help enable data exchanges through software, bridging these islands using fixed formats that give operations a similar look and feel. Sharing is successful because the data are unified, consistent, and compatible.”
3. Factory islands reach across the enterprise and include the upper-level communications critical to management. Data exchange traditionally has required a lot of hardware and software to create, collect, and maintain the information. However, says McAtee, the integration of software tools such as OPCUA into upper-level systems is simplifying the process and barriers are falling.
Burke elaborated on the concept. “Today, islands of information need to be tightly integrated as companies strive to improve the bottom line through the timely exchange of data between disparate systems. Years ago, when proprietary systems dominated factory and process applications, few worried about data integration, whether between components or across the corporate firewalls. There was no Internet, as we know it today. Now everyone wants all types of information integrated, securely and reliably.”
Making it easier, simpler with software
Open technologies such as OPC and its iterations— along with advancements in and variations of Ethernet, the de facto standard of enterprise systems today—have literally opened the door to the sophisticated interoperability connecting heretofore separate automation processes. Standard protocols are understandable, flexible, cost effective, and, of course, open. They, more than any other factor, are enabling control systems to talk to each other. Benefits such as Web features, routine at the enterprise layer, are migrating to the controls world, and as more manufacturers incorporate these technologies, more and more ways are being found to extend their use.
A caveat, however: Just because a communication protocol is a “standard” doesn’t mean it is open, stressed Stubbs.A truly open protocol, he said, must have three characteristics:
1. The protocol must be an international standard (for example, IEC or IEEE). The specification must be available for purchase directly from the standards body.
2. The intellectual property (IP) owner must allow competitors and third parties to implement the protocol in their systems or devices.
3. Third-party devices must be readily configurable in all control systems, especially the controller of the IP owner.
“More than any other factor, customer demand and need to connect disparate products have driven interconnectivity and interoperability to present levels,” said Tony Paine, president, Kepware. “Before OPC, vendors had to build a connector for the driver each time they wanted to connect to a component. They reached a point where they didn’t want the inability to connect to be a barrier to selling products and began to create tool kits enabling end users and OEMs to build their own communications methods. But systems were still tied to one vendor’s technology. Then a number of leading automation suppliers created a specification for process control and manufacturing automation applications (OPC) that would facilitate interoperability based on the latest Microsoft technology at the time. The result has been the development of hundreds of applications that support OPC data access, fostering the ability to read and write information from devices, components, and systems over a common interface.”
The cooperation and consistency that emerged turned out to be good business, and also a catalyst that pushed user expectations to the next level. Once interoperability was available on the plant floor, companies wanted plantto- plant communication and data sharing. “OPC standards and specifications continue to help do this,” added Paine, citing OPC-UA, which helps communications run securely over the Internet, among the most recent developments. (Read more about OPC and OPC-UA in the accompanying sidebar, OPC: The Next Generation.)
Applying the power of Ethernet
As open protocols have helped join disparate systems in one way, Ethernet and its variations and advancements have influenced it in others. It didn’t take long after inception for Ethernet to become the de facto standard for enterprise systems. Then—with advancements many said would never happen—it moved into fieldbustype networks and the automation space. A variety of Ethernet-based networking protocols are now available and finding their way into the automation space. (Read more about the types of Ethernet in the accompanying sidebar, Multiple Flavors of Ethernet.)
“There are a lot of Ethernet-based protocols out there,” said Mike Hannah, manager, Ether- Net/IP networks, Rockwell Automation. “Unlike EtherNet/IP, many are dedicated networks intended for specific purposes, so that even though they allow interoperability at a certain level, integrating disparate functions—motion, I/O, and operator interfaces, for example—into control rooms in the enterprise space can still be complicated, typically requiring additional programming and gateways to move the data.”
Indeed, Ethernet isn’t interoperable in and of itself, but it does help hardware exchange data and make information sharing between machines faster, better, and simpler. “Years back,” added Kepware’s Paine, “if HMI packages were installed on two machines to collect data from several devices, each polling for the same information, depending on the timing, two operators might see different information on their screens. Ethernet allowed distributed architectures. An OPC server on one machine now can act as a gateway so that all HMIs or client applications gather data from one source and display the same thing at the same time.”
“As little as two years ago,” continued Hannah, “multiple network systems were common on the plant floor. It was cumbersome to get data from the source to where it was needed for decision making. Single network solutions like EtherNet/IP (standard Ethernet TCP/IP using CIP, ODVA’s Common Industrial Protocol) are desired in the automation space; a network that can coexist with an IT Ethernet network (Ethernet IP) allows information, motion control, safety, I/O, and peer-to-peer control to be done over the same wire.”
Ethernet’s ability to play in the automation space continues to surprise some, who say it is not deterministic enough for many control system functions. “That is somewhat true that Ethernet is not deterministic by nature,” admitted Hannah, “but again, advancing Ethernet technologies, like IEEE 1588, Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems, for instance, eliminates the need for proxies and ‘store and forward’ products when connecting control systems together. This precision time protocol allows the creation of a deterministic network and enables functions like high precision motion and sequenced alarms and events to run on the same network as the information systems.”
Not your universal translator, but…
Integration is still not a clean and simple process. However, enormous strides have been made. Look for more to be made in the future. Manufacturers must recognize that innumerable options and alternatives exist and exercise care in making connectivity decisions. There are as many ways to bring control systems together or push data to the enterprise are as there are manufacturing facilities.
Possibilities are endless as interoperability and data exchange once only imagined become reality. If a system has information in it, someone likely is working on a way to retrieve it and bring it to the PC. The bigger hurdles today stem from organizational attitudes. Bridging that cultural gap between IT and manufacturing is real, and perhaps more challenging than implementing technology. “Much of what we’re doing on the control side today is not necessarily new,” said McAtee. “The most significant barriers keeping control systems apart are not technological. Resistance to change tends to slow the process."
Two sidebar discussions, also part of this Control Engineering December 2010 feature article, are:
• Multiple flavors of Ethernet – with additional graphics
ONLINE extras: Read how two companies used integration tools to connect systems and boost efficiency.
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