Peter King is in the middle of a major merger that will restructure his entire operation. This merger is not related to a business acquisition, however. Rather, this is a restructuring and a technology consolidation of the company's distributed control systems.
King, control systems superintendent at Tesoro Refining and Marketing, an oil refinery in Martinez, CA, is combining 14 separate control rooms into one. As part of the move to a centralized operation, the company is gathering all of its existing distributed control systems (DCS) into a large, plant-wide operations center.
"The driving force behind this is to improve operating efficiencies and savings through advanced process control and have better coordination to support the plant," says King. "It is also to try to move our organization out of the 1950s and into the 2000s."
As King began to take steps to upgrade his decades-old legacy control systems with technology capable of supporting a data-intensive environment, however, he, like many other plant managers, was surprised to find that control architectures have changed drastically. There used to be a clear defining line between what a DCS did -- control process-oriented devices and operations -- and what a programmable logic controller (PLC) did, mainly control specific equipment functions in discrete manufacturing environments. Recently, these two worlds have begun to collide, with the DCS and the PLC adopting functions that cut across both discrete and process environments. Some industry observers have begun to call this "hybrid control" technology.
EVOLVING TECHNOLOGY
"We see the evolution of the DCS into CPAS, or a collaborative process automation system," says Larry O'Brien, research director at ARC Advisory Group. "It is moving toward a system architecture that encompasses a lot of things the DCS didn't traditionally encompass, such as operations and production management, logic control, continuous batch and integrated safety. CPAS has a common hardware architecture, a common presentation layer and a common network architecture."
Similarly, the traditional programmable logic controller is morphing into what ARC dubs the programmable automation controller (PAC), which blends logic, motion and process control on a common development platform to speed deployment and ease the learning curve.
SIMILAR, BUT DIFFERENT
The differences between PAC and CPAS are -- and will continue to be -- scalability and, to some extent, functionality. PACs can accommodate small process applications, but could never tackle the large bursts of continuous data that move through big batch environments. At the high end, where the DCS will continue to play, high-speed networking, diagnostics and alarm management are being built in. (Click here for a select list of companies that offer DCS products.)
At Tesoro Refining, King is using Foxboro Automation Systems' (a unit of Invensys Process Systems) I/A Series version 8.0 -- a CPAS-style system -- as its single DCS around which it will merge 14 control rooms into one. The system sits in a newly-constructed control building where it manages oil refinery processes, some of which are a few miles away. Version 8.0 replaces earlier versions of the I/A Series at Tesoro, which lessens the engineering effort the company faces during the upgrade. But, more importantly, King says, version 8.0 comes with a high-availability mesh network including 1 gigabit Ethernet switches.
"The bandwidth is so large, you don't worry about it," says King. "The system can handle so much more data then we are ever likely to use it for ... we don't have to be so concerned with calculating communication loads."
The I/A Series also includes field device integrator I/O modules that make it easy to add third-party devices via OPC, Modbus, ControlLogix and other communication protocols. "Customers want to take all of their plant devices and make sure they talk to each other in a convenient way that is easy to set up," explains Paul Steinitz, Foxboro's director of marketing. "They can look at the entire plant as a whole, not as individual pockets." Steinitz says this trend is driven by control room consolidations and the need to make the plant operator smarter.
PAC IT ALL IN
Meanwhile, on the PLC side, Rockwell Automation (Milwaukee) is even evolving its flagship product to take on some characteristics that were previously the domain of the DCS. "We call it the new generation controller," which is based on the company's ControlLogix platform, says Mike Miclot, Rockwell Automation's director of commercial marketing. "The PLC doesn't play well in process. But the PAC does more than the PLC ... it is crossing over to the DCS."
For example, this month, Rockwell Automation will roll out its PhaseManager, a feature within the ControlLogix PAC architecture that embeds the ISA's S88 batch management model within the controller, which will separate the logic (detecting the state of the equipment) from the recipe (what is being made). This allows the PLC to keep equipment running while it also manages the batch, a task traditionally handled by a separate controller.
PhaseManager can also be coupled with BizWare Batch, a recipe management application that will be available from Rockwell in September. "To DCS users this will be very intuitive," Miclot says.
The other intuitive aspect of the Rockwell Automation PAC is that data is defined in tags that use the customers' own nomenclatures, he says. That means, rather than having memory registered in bits, as it would be in a PLC, it can be read, understood and, more importantly, transferred to other applications such as a manufacturing execution system (MES) or an enterprise application.
Being able to turn data into information represents a big transition for controllers. Adherence to standards has helped PLCs make that transition. "There are more [customers] wanting [the technology] to sit on standards and wanting a higher-level programming language and more object-oriented control," says Connie Chick, controller business manager at GE Fanuc Automation Inc. (Charlottesville, VA). That's why GE Fanuc's PACSystems are built around a universal programming environment and support communication standards such as OPC (OLE for Process Control). Next year, the company will add new process capabilities and high-speed networking options. (Click here for a select list of companies that offer PLC products.)
THE ROAD AHEAD
Regardless of whether a buyer is looking to invest in a CPAS or a PAC, it is important to ask about the vendor's future technology roadmap. "I would emphasize the business angle and not just evaluate suppliers' technology," says ARC's O'Brien. "It's important to understand where the supplier is headed in the next five years." For example, says O'Brien, you should examine vendors' product migration strategies, commitment to standards and understanding of key business processes that are important to you.
Indeed, more and more customers are requiring that the vendor help them manage the lifecycle of the system in order to minimize the amount of change and keep everything up and running. For its part, Siemens (Alpharetta, GA) has crafted an incremental migration strategy from its own APACS+ DCS platform, along with third-party vendor products, to its new SIMATIC PCS 7 process control architecture. "We developed products that allow you to break up the new and old systems and bring together the portions of the old that you want to keep with what is necessary in the new system," says Todd Stauffer, Siemens manager of product marketing. That includes conversion tools, communication gateways and even services that can convert a manufacturer's intellectual property to the new environment.
NO RADICAL STEPS
Having the tools and the intelligence behind the upgrade is important because rip and replace could cost too much time and money to be practical. More than likely, most manufacturers, such as Tesoro's King, are buying into a gradual migration strategy.
"This is a complex process," says King, who is just starting to connect all of the old DCSs into the new centralized system. "There is a technical issue, as well as human factors and safety. To bring it all together you have to be prepared to accept it will be complicated. There are a lot of things that have to happen simultaneously, so it needs to be well planned to be successful."