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Gaining an edge in automation

21 May 2019

Edge computing advances give users more options for architecting automation systems, flexible communications and programming choices, says Benson Hougland.

Traditional automation architectures are built around centralised programmable controllers connected to remote field devices and instruments. This concept is shifting as computing power is progressively embedded near the edge of automation systems using new types of intelligent components. Edge computing designs offer some advantages compared to traditional and more centralised strategies.

Combine and conquer
Edge computing benefits designers and manufacturers by consolidating components and configurations. An edge programmable industrial controller combines input/output (I/O), control, data processing, communications, and human-machine interface (HMI) functionality that can be located near or on machines, process trains or smart equipment.

An on-board touchscreen display, with options for a larger local monitor, is useful for machine manufacturers since control and visualisation are effectively merged. This makes commissioning, operating and troubleshooting easier since a separate PC is not required. Local operator functions, such as pushbuttons and indicators, can be handled on the HMI more effectively than traditional pilot devices. Edge computing makes it easier for users to incrementally roll out system improvements. Instead of affecting large in-service installations, an edge computing system can be installed and tested locally and merged into the larger system via a quick hot cutover.

Shifting communications and data processing to the edge makes sense for many reasons. Control decisions are made in real time where they are needed. Data is obtained, pre-processed, and analysed near the source. This reduces the required network bandwidth, data storage, and processing power upstream of the edge component.

Programming for these edge components can take many forms. Traditional programmable logic controller (PLC) users usually will look for ladder logic or other IEC 61131-3 programming languages. Flowchart-based programming language is often better suited for the application. Python or C/C++ might be preferred for more advanced calculations and data processing. Some edge computers can accommodate these programming languages and others.

Communications flexibility is another hallmark of edge computing. An edge programmable industrial controller has various communication ports and supports a wide range of protocols so it can connect with numerous local intelligent systems, such as PLCs. 

Edge computing components support operations technology (OT) protocols such EtherNet/IP, Modbus, BACnet, those from OPC Foundation, and others. It also supports information technology (IT) protocols and development tools such as TCP/IP, simple network management protocol (SNMP), message queuing telemetry transport (MQTT), and Node-RED. This suite of interfaces effectively “flattens” and simplifies the system architecture and system integration.

Edge computing is suited for gathering the right data in the field, processing it into useful information, and securely communicating it to higher-level data architectures. Edge computing can interact with other supervisory on-site automation platforms, enterprise databases, or even exchange data with cloud services.

Picking the right system
When designing a control system, users select the best set of features. That has meant relying on more centralized platforms, which are functional, but also impose constraints. The expanding abilities of edge computing give designers and engineers new options. Edge computing can combine as much or as little I/O connections, control, communication, data processing and HMI visualization functionality as needed. 

Edge computing is often an ideal solution for users needing granular, modular, and scalable architectures that can fulfill many requirements. 

Benson Hougland is vice president of marketing at Opto 22. 

This article originally appeared on www.controleng.com


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