From Programmable Logic Controllers to Edge Computing – How Control Systems are Advancing to Industry 4.0

Before the 1970s, companies operating industrial processes used simple devices such as relays and interlocks to achieve a minimal degree of automation and control. During the 1970s, Programmable Logic Controllers (PLCs) were developed to replace relay-based systems. While PLCs offer much greater flexibility for programming compared to relay-based systems, they were still programmed using ladder-logic to mimic the appearance of wiring diagrams. In the early 2000s, some of the first Programmable Automation Controllers (PACs) were engineered. PACs provide a single platform that operates in multiple domains such as motion, discrete, and process control applications. More importantly, PACs provide a more open and modular architecture to integrate and interoperate with other devices, networks and enterprise systems. While PACs offer a higher level of flexibility and interoperability with enterprise systems compared to PLCs, they are unable to dynamically adjust to changing business objectives and are viewed as static components, infrequently changed and heavily constrained by design spec at installation.

 Edge controllers offer a generational advancement to PAC-based industrial control systems by enabling safe, secure communication between real-time deterministic control and non-deterministic applications that leverage external data to analyze and optimize business operations (Fig 1). Edge controllers provide software-defined controls with enhanced optimization capabilities while maintaining the stringent safety and security required in industrial applications. These new controllers utilize edge technology running on a general-purpose operating system such as Linux next to the real-time deterministic control to optimize control processes by leveraging data and analytics from external sources such as enterprise, ecological and environmental databases via the industrial internet. On today’s PACs, customers can write rudimentary analytics utilizing IEC61131-3 languages; Edge controllers enable modern programming languages such as C/C++, Python and Java that can be used to apply complex optimization algorithms or analytics to operations without impacting the control process. This allows the incorporation of an “outer loop,” an “advise” layer on top of the typical “see-think-do” control loop that can optimize the control application.

 How does it solve or meet the challenges for Industry 4.0? In an oil and gas pipeline control application, the edge controller can be used to fly a drone to verify the fault that is raised by the real-time deterministic control. By taking advantage of the connectivity provided by this technology solution, the operator can have a live image/video feed of the actual situation relayed directed by the edge controller and do a visual inspection of the fault raised by the control system in real time. The operator can then decide how to resolve the issue before even dispatching the maintenance person to the remote area, thereby reducing the unplanned downtime significantly.

There’s much more to learn about edge controllers and you can get some additional information HERE. How are you using edge computing in your applications?