Distributed ControlA Distributed Control System was an elaborate, monolithic network of microprocessors that controlled various aspects of a process system. They were complex and expensive, and typically used proprietary hardware and software including control languages, so only the company that built them could service and support them. And once the system was in place, it was difficult to adapt as your process requirements changed over time. But they were capable of handling the largest and most complex processing systems, making them a major step forward for continuous processing industries like Power & Energy, Oil & Gas, Water & Wastewater, and Pulp & Paper. Programmable LogicProgrammable Logic Controllers, or PLCs, were small fast computers developed to control one or more real-world processes, such as equipment in a process system. They replaced hard-wired relays that had to be rewired by hand with each modification to the process or product, making changes costly and inefficient. With a PLC, all you had to do was reprogram it. Early PLCs actually used ladder logic that mirrored a relay diagram so that traditional engineers would be able to read them easily. Where DCSs were rigid, PLCs were flexible. Where DCSs were large, self-enclosed systems, PLCs were modular and scalable, making them good solutions for small and medium-sized process systems, especially in batch and discrete sectors like Food & Beverage, Personal Care, and Life Sciences. And because they were modular they were generally less expensive, at least at the beginning of a project. By the time engineers had built the components into a system, however, their price point could rival or at times exceed the cost of a DCS. The Hybrid PromiseIn the last decade, both historic DCS and PLC companies have moved toward a space that both call "hybrid," in which they attempt to offer the power and complexity of DCSs and the flexibility, openness and low cost of PLC systems. DCS companies have done this by reducing the footprint of their systems while PLC companies have begun linking their components together to create more complete systems. But though many were commercially successful, these "hybrid systems" have never fully delivered on the original hybrid promise. For one thing, the DCS hybrids have been unable to tailor their systems to become modular enough to work with both OEMs & End Users and scaleable, flexible enough to handle applications that range from small to large. In addition, the speeds of high speed sequential or discrete processes — sometimes measured in the tens of milliseconds — are typically too fast for DCS hybrids to accommodate making applications like packaging or metal stamping or simple motor control difficult if not impossible to control. So a hybrid plant with batch, continuous and discrete environments or a large continuous processing plant with high speed sequential control needs as well still had to acquire a second process system for their discrete areas, with all the extra cost, integration problems, increased training and maintenance that entailed. Many of the historic PLC systems attempting to deliver Hybrid Systems fell short of offering true system capability often lacking system services such as global namespace and system alarming / eventing to name a few. Whether from the traditional DCS or PLC technology heritage, most all these systems fell short of tightly integrating with the information layer. Closing the information and automation gap to effectively control and optimize production and increase performance of operations was done in multiple systems with multiple databases driving high costs of ownership. Contextualized role based visibility into process operations was simply not economically available. Delivering on the Hybrid Promise, Closing the Information and Automation GapNow, GE Fanuc introduces Proficy Process Systems, a Process automation and control system that delivers on the hybrid promise, providing the power and effectiveness of a distributed control system with the flexibility, openness and price affordability associated with programmable logic controllers. With our Proficy software layer inherently architected into our process control system, optimization and analytics, production management are simply layered on. Partnering with GE Fanuc for your process control needs provides benefits that can give you the edge in today's competitive global economy:
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