Controllers, interfaces provide advanced edge computing capabilities

Edge computing insights

• Edge controllers provide computing and advanced communications capabilities, but may be too complex or expensive for smaller applications.
• Modern programmable logic controllers (PLCs) go beyond the real-time control of legacy PLCs, with edge computing features that can support data gathering and analytics needed for more flexible production and greater efficiency.

More than ever before, consumers now want to have it their way with many different types of products, and manufacturers need advanced automation and controls to install at the edge and support consumer demands. Manufacturing flexibility presents a problem because mass production and standardization are typically the best formula for efficiency and cost reduction, yet these concepts do not mesh well with consumer demand for more customized products.

Responding to consumers, many industries are turning to data-driven solutions to improve the responsiveness and quality of products, services and manufacturing. This in turn has led to deeper integration of operational technology (OT) production systems with information technology (IT) enterprise systems, and edge computing can help.

Such integration is necessary not only for mass customization, but also to collect and process data for continuous improvement, quality control and track-and-trace efforts. This data also has been foundational for predictive, prescriptive and descriptive analytics.

Data is the key to enabling dynamic changes for agile production, and for optimizing operation and energy consumption. For these reasons, industrial companies are looking for the most effective ways to connect with the valuable data contained within their manufacturing systems and put it to good use. How can industrial automation designers, especially original equipment manufacturers (OEMs), adapt to the growing need for data and deep integration with enterprise systems?

Manufacturing products, with data on side

Manufacturing systems clearly produce products, and they increasingly are producing data also. More data is being created today than at any point in history. According to the Domo, creators of “Data Never Sleeps” infographics, over the past decade the total amount of data predicted to be created, captured, copied and consumed globally in 2022 is 97 zettabytes (ZB). Manufacturing leads the way, with more data stored than any other sector, including government.

To generate and handle these data volumes, there has been a massive expansion of digital transformation, smart devices and industrial internet of things (IIoT) technologies implemented throughout industry. Most manufacturers and OEMs are recognizing the data generated by their control and monitoring systems on the plant floor is digital gold, but only if it can be easily accessed and quickly acted upon.

Just as there are more source of data than ever, there are more technology options for connecting with this data. Connecting with, contextualizing, transmitting and processing large data sets can be complex and costly because of the required infrastructure and security.

Figure 1: Significant and valuable data is available from PLCs and IIoT devices at the operational edge, and there are now many options for communicating this data via edge controllers to on-site or cloud-based resources for monitoring and analysis. Courtesy: AutomationDirect

Manufacturing data collection and analytics, then and now

For users attempting to access and act upon industrial data sources, the challenge has been connecting with a variety of edge-located target devices, and then transporting and storing the data to where computing and analytics can be performed (Figure 1).

Traditionally, industrial automation systems have been designed with programmable logic controllers (PLCs) and human-machine interfaces (HMIs) to provide basic control and monitoring functionality. In a typical scenario, data might then be collected via an OPC data server and contextualized in a data historian or supervisory control and data acquisition (SCADA) system.

The PLCs, HMI/SCADA, and historian were generally segregated from the IT infrastructure. As these OT devices improved, along with the associated networking and communication protocol technology, it became simpler to collect data, even to the extent OT devices could interact more directly with IT systems.

OT and IT convergence has led to another key development, which is a newer class of industrial control and computing device – often called an edge controller. An edge controller generally combines real-time PLC control with general-purpose PLC/SCADA computing and communications capabilities. Edge controllers communicate well with OT and IT assets, and they also enable storage and computing resources to shift from a central data center or the cloud, to an edge location where the data is generated (Figure 1).

An edge controller can be attractive for some applications, but one consequence of this device is the technology stack becomes much deeper, so the overall cost and required development time may not be practical for many OEM machine builders or smaller end user applications.

Figure 2: Instead of developing custom platforms or over-specifying edge controllers, OEMs and designers can use today’s PLCs to automate their equipment and provide easy connectivity. Courtesy: AutomationDirect

A practical data access approach for edge controllers

Machine builders will always preserve a primary focus on robust real-time control and convenient visualization, even as secure remote connectivity, data access and agile production are becoming more important.

In some specialized cases, such as machines with annual production runs in the tens of thousands, it might make sense to develop custom control, computing and connectivity solutions. And in other cases, a project might support the cost of an edge controller and associated development.

However, the reality is a large portion of machine, and even small- to mid-sized general automation applications, are readily served by modern PLCs and HMIs, even where data access is a priority (Figure 2).

This is because modern versions of these devices have incorporated networking, data handling, and processing features, so they can fulfill much of the IT accessibility requirements, but at a reasonable cost and with straightforward implementation. They support edge computing needs, such as remote connectivity and advanced monitoring and analytical integration. This is evident in at least three specific aspects of modern PLCs:

1. Networking and communication: Modbus, EtherNet/IP, and Profinet are some of the most popular OT-based communications protocols, or fieldbuses, that many modern – and even some legacy – PLCs support. But until recently, it has been much rarer for PLCs to include protocols allowing them to seamlessly integrate with enterprise systems. Furthermore, encryption, data privacy, and other cybersecurity concerns were either not addressed or added as afterthoughts. However, some modern PLCs incorporate IT functionality natively in the communication stack by supporting OPC UA, secure integration with local and enterprise email services, Microsoft certified Azure integration, secure REST API, and secure message queuing telemetry transport (MQTT) with Sparkplug B, in addition to a host of fieldbus protocols (Figure 3).
2. Data contextualization: Legacy PLCs often contained unstructured data, which required significant rework at the supervisory layer to prepare it for consumption by enterprise systems. Modern PLC software allows automation designers to create this structure and definition one time at the source of data, and the PLC firmware can expose the data model for consumption, resulting in a “single source of truth” for systems consuming the data.
3. Low-latency data processing: Aggregating data locally at the edge typically wasn’t possible with legacy PLCs because of memory and other computing resource constraints, or it was considered a low priority compared with executing control code. Modern PLCs balance memory and processing to allow basic data collection and aggregation locally, while prioritizing execution of real-time control code. This pre-processing is most effective when performed on low-latency data at the source, and it reduces the amount of upstream network traffic and processing required for data intake and transformation.

With modern PLCs, designers now have scalable options to develop reliable future-ready automation to integrate with enterprise systems, providing edge computing functionality.

COVER: Edge computing capabilities require integration on multiple levels. The AutomationDirect BRX PLC can communicate with a wide variety of OT devices using popular fieldbuses, and it can interact with higher level IT systems using many different methods. Courtesy: AutomationDirect

PLCs go beyond basic automation

Industrial automation designers, especially OEMs, pursue standardized solutions to make equipment easier to develop, operate and maintain. However, some developers may be concerned about investing in a standardized solution, which might limit innovation as their product range and needs expand.

Modern PLCs and HMIs can address these issues because they help ensure reliable overall functionality with the capability to execute essential tasks now while performing more advanced computing in the future.

Users can implement this type of edge technology today to deliver right-sized and cost-effective automation using familiar platforms while leaving the door open to create more advanced applications, such as edge computing functions, as needed. Higher-level IIoT platforms, cloud computing and even sophisticated strategies such as machine learning (ML) can now interact directly and securely with OT digital assets, without requiring complex intermediary steps.

This brave new world of PLCs and HMIs provides designers with the real-time control capabilities they need now, while adding functionality for data handling and access. Abundant computing resources within these devices also provide platforms to handle future needs, both anticipated and unexpected.

Damon Purvis is the PLC product manager at AutomationDirect.com. Edited by Chris Vavra, web content manager, Control Engineering, CFE Media and Technology, cvavra@cfemedia.com.

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