Choosing a control system: PLC or DCS

Today, the economic pressures facing us are at levels few have ever seen. These challenges make it all the more imperative to select the technology that is right for you. Focusing on the requirements of the application and of the key stakeholders should always be your guiding principle.

03/01/2009


Today, the economic pressures facing us (and our companies) are at levels few have ever seen. These challenges make it all the more imperative to select the technology that is right for you. Focusing on the requirements of the application and of the key stakeholders (engineering, maintenance and operations) should always be your guiding principle. No one can afford to select a system based solely on technology (what it can do). More importantly is what it can do for you. Productivity, efficiency, safety, energy savings and long-term supportability are among the criteria that should guide your decision.

Many of the classic stereotypes of when to use a programmable logic controller or when to use a distributed control system have become clouded. In fact, the key differences between a PLC and DCS are no longer in the hardware. Microprocessor advancements have made the controller in a PLC system virtually indistinguishable from that in a DCS. The real differences now are in the software and in the application libraries (domain expertise) that come with these products.

To help determine the best technology for your application it is important to objectively document your requirements. To enhance this process, ask some important questions of the major stakeholders in the plant. This will help you determine whether a PLC or DCS system is best for you.

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