When you trace the evolution of control systems from PLCs to PACs to today’s edge controllers, the focus becomes increasingly on the close link between the control system and the business outcome. One of the key advantages in achieving those outcomes is the ability to perform rapid prototyping. Implementing, for example, less than a six-month deployment on control systems gives customers the ability to experiment and calculate real ROI on expanding their solutions. How is this possible? In a recent presentation, Kyle Hable, IIoT/Edge product manager for machine automation solutions, discussed the potential for just such capabilities.
Since there are all kinds of definitions of the “edge” floating around in industry, Kyle began by clarifying that the edge in this context is the edge of the control network as shown in Figure 1. Kyle says, “As the IEC 61131 standard for programmable controllers (PLC) continues to evolve, we’ve followed a consistent trend towards scriptable, textual languages. Ladder Logic is increasingly playing a minor role in state-of-the-art control systems. In the past you could order a co-processing module to run general purpose operating systems like Windows or Linux that could be inserted alongside your 61131 runtime. This created a whole new paradigm of what you could do with a PLC. Today, as technology evolves at a pace more rapid than it ever has, we have introduced a new standard into our line of PLCs. With the introduction of our CPL410 PLC, the general-purpose operating system and its wealth of available runtimes, connectors and data processing applications are paired, not as an option, but as a standard feature.”
Kyle then went on to explain the “left brain/right brain” hypervised control. “Running two operating systems, one real-time and one general-purpose, on one piece of hardware is a monumental feat in and of itself. Further allowing them to communicate with each other using a secure, standard, open, shared memory interface via OPC UA is picking up where the co-processor modules of the past left off.”
Figure 2 shows the structure of advanced edge-based computing for PLCs and PACs, which enables local applications to be written in common languages including Python, PHP, C++, Java, JavaScript, Ruby, and more. This, in turn, promotes the pathway to web-based communications and applications. Applications can be run in isolation locally or on the intranet or even internet, but any security attack from the interface is minimized into a single attack vector, allowing the 611131 control strategy to remain unaffected. Basic building blocks include: Open VPN, Apache Web Server, SQLite, Docker, Docker compose, Python and Node RED.
Enabling new languages provides better flexibility in implementing fully automated solutions and we can create value in adding tools that are built or written in the new languages.
Kyle says, “Node-RED for instance, runs on top of Node.JS and gives us another graphical programming paradigm that we first saw with Ladder Logic, further compounding the options our users have to build out solutions.”
Node Red allows users to quickly develop edge sensor connections, data aggregation, calculations, trending, local dashboards, publishing to endpoints and REST APIs. Similar results accrue with Grafana, a rapid prototyping software, plus the CPL410 is the first PLC certified for Amazon Web Services (AWS) IoT Greengrass.
In the presentation, Kyle described complex applications that have taken advantage of edge computing, including highway tunnels that needed aggregated system status and fault information provided remotely. Capabilities and outcomes include:
Business results included reduced maintenance costs through intelligent workforce routing, increased tunnel up-time, traffic throughput and reduced emissions.
In another example, in a gas turbine combustion development and test case, combining the two systems using the CPL410 can save up to 50 minutes per test, resulting in a potential of $1MM of reduced costs per year.
Moving control closer to the edge speeds development time and achieves more effective business outcomes.
How are you using edge control in your applications?
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