Open automation with plug and play

Plug-and-play and non-proprietary open automation system designs have become the goal of users. Many interoperability efforts include the O-PAS standard for control system architecture, time-sensitive networking (TSN) for industrial Ethernet and IEC 61499 for programming.

By Stone Shi November 27, 2021
Courtesy: Chris Vavra, CFE Media and Technology


Learning Objectives

  • Examine the development process of open automation: DCS, fieldbus, programming.
  • Push for a higher level of industrial control system openness in a new era.
  • Renew the journey toward more open automation using IEC 61499.

Automation and controls are becoming more open and interoperable and standards O-PAS standard for control system architecture, time-sensitive networking (TSN) for Industrial Ethernet and IEC 61499 for programming. For a long time, in the field of industrial automation, control systems are often relatively closed proprietary systems for the sake of reliability, safety and unique technology. Closed control systems have played a great role in promoting industrial production in the past few decades.

However, with the progress of technology and the intensification of global market competition, the flexibility, agility and maintainability of production have become the focus of industrial enterprises.

The disadvantages of proprietary control systems with non-open and poor compatibility have gradually become prominent. Especially under the trend of continuous integration of information technologies (IT) such as Internet of Things (IoT), Big Data, artificial intelligence (AI), object-oriented and service-oriented architecture applied to operational technology (OT) implementations, the openness of control systems is more important. Plug-and-play and non-proprietary open automation systems have gradually become the goal of users.

The process of open automation: DCS, fieldbus, programming

In fact, the limitations of proprietary automation systems are not recent. Early distributed control systems (DCS) used proprietary networks to communicate. The systems were completely closed. The products of various manufacturers formed their own systems. Equipment from different manufacturers, whether instruments or input/output (I/O) devices, could not be interconnected. Fieldbus technology, which began to rise in the middle and late 1980s, has changed the closed and dedicated communication network into an open and standardized network, which can connect the automation equipment from different manufacturers that comply with the same protocol specification used in control systems. However more than 10 common industrial fieldbuses have formed in the world because of industry interests and regional developments.

In the 21st century, Ethernet based on TCP/IP entered the field of automation. Industrial Ethernet with slight modification on the standard Ethernet protocol has brought greater openness to automation systems. Real-time industrial Ethernet began to rise in the field of motion control. These industrial Ethernet protocols are open protocols, some are free, some are open-source and some have become China’s national standards. The applications of industrial Ethernet make it possible for more equipment and more systems to access the control system, “one network to the end.” Unfortunately, like fieldbus, industrial Ethernet has not been unified into a protocol standard for various reasons. Major manufacturers do their own things and need protocol converters to connect with each other.

In addition to the opening of the network, the hardware and software of automation control systems have been moving toward openness. In the 1990s, PC-based control technology began to rise. Industrial PCs (IPCs) and embedded PCs began assuming the role of industrial controller, which made industrial computers equipped with Microsoft Windows or Linux, even commercial computers or laptops become controller hardware without relying on hardware manufacturers. Many IT technologies can be used on industrial computers serving as controllers, which brings greater openness to the automatic control system.

In terms of software, most manufacturers have programming software or configuration software. In the early 1990s, IEC 61131-3 was formed to standardize programing for automation systems: programmable logic controllers (PLC), DCS, IPCs, computer numerical controllers (CNC) and supervisory control and data acquisitions (SCADA) programming systems. [Many programming software packages use parts or all of this standard, but code created with different manufacturers’ implementations of the standard isn’t necessarily interoperable.]

Some manufacturers and organizations are promoting the openness of control system architecture. For example, in 2016, ExxonMobil launched through the open process automation forum (OPAF) to define “an open, secure, standards based, interoperable and applicable process control architecture for multiple process industries,” that is, the Open Process Automation Standard (O-PAS), organized by the Open Group. In addition, the German process industry user organization (NAMUR) has proposed its open architecture NOA [in collaboration with the Open Group] and plans to release it in accordance with IEC standards from 2021 to 2022.

Higher-level industrial control system openness in a new era

Manufacturers and users have been pursuing open automation at all levels. However, due to technology and obstacles, automation still isn’t very open. There are still many kinds of industrial communication standards, and they are still difficult to interconnect with equipment of different manufacturers. Although PLCs developed by various manufacturers support IEC 61131-3, hardware isn’t interchangeable, software often isn’t compatible, and programs cannot be reused from one manufacturer’s PLC to another.

Is there a higher level of openness, so automation equipment can be plug and play like IT equipment? The good news is this kind of open automation is beginning to happen.

In terms of interconnections, TSN has been supported by most manufacturers. OPC UA from the OPC Foundation has become the main information model in semantic interoperability. Edge controllers based on IPCs and real-time operating systems appear to be a mainstream trend. A higher-level open standard, IEC 61499, has started to gain industry support to help with software reuse and hardware-software decoupling.

Like IEC 61131-3, IEC 61499 includes function block-based graphic programming method. However, the difference is IEC 61131-3 is a program-execution process based on time scanning, while IEC 61499 is an event-driven function block network, which is more in line with modern software engineering. The function block provides a unified interface package for logic code, and the function blocks are connected with each other through event and data interfaces.

Function block programming is the core concept of IEC 61499. Its purpose is to use the object-oriented programming idea to package the industrial control software into software components in the form of function blocks. The function blocks can be written in IEC 61131-3 programming language or C++ and other high-level languages and have nothing to do with hardware equipment resources.

By proposing an application model independent of the underlying system equipment, the IEC 61499 standard realizes the portability of application code across more vendor platforms and engineering design tools. Through the standardized packaging of function blocks, the reusability of software is realized to decouple software and hardware. The event-driven feature is suitable for interaction, so advanced IT technology can be integrated into automation systems. These characteristics of IEC 61499 are laying the foundation for the establishment of a plug-and-play, fully open and interoperable automation system.

Because of these reasons, OPAF and NAMUR take the IEC 61499 standard as one of the main recommended standards for their open architectures.

Renewed journey of open automation using IEC 61499

IEC 61499 standard has been published for 15 years, but its practical application progress has been slow. On the one hand, there must be a lag in the development cycle between the formulation and implementation of the standard, most importantly because of technical constraints, especially the lack of IEC 61499 software development platforms. More users are used to developing applications on the software platforms of several major automation manufacturers that only support IEC 61131-3.

The first industrial implementation of IEC 61499 was ISaGraf, but it did not implement all IEC 61499 specifications. Later, the Eclipse Foundation created 4diac, an open-source project of IEC 61499, and cultivated some development applications. In addition, the nxtControl company registered in Austria has persisted for more than 10 years with effective work on the application development platform and industrialization of IEC 61499.

Automation manufacturers have not shown much enthusiasm for IEC 61499. However, that changed with 2017’s Schneider Electric’s acquisition of nxtControl. In October 2020, Schneider Electric officially released the open automation platform (EcoStruxure Automation Expert) based on the IEC 61499 standard.

Using the IEC 61499 standard, EcoStruxure open automation platform enables automation applications to be built using asset centric, portable and proven software components without relying on the underlying hardware infrastructure. Users can distribute applications to any selected system hardware architecture that supports IEC 61499 standard without additional programming work. Support for proven software best practices simplifies creation of automated applications that interoperate with its systems.

Compared with traditional automation systems, using the EcoStruxure open automation platform can shorten the time required to perform traditional automation tasks 2 to 7 times, increase the speed of users developing innovative applications by 3 times and eliminate faults by 6 times, according to Schneider Electric.

It’s time to take bold action in the field of industrial automation, and Schneider Electric calls on industrial users, original equipment manufacturers (OEMs), system integrators and engineering, procurement and construction (EPC) contractors to embrace open automation.

It’s time for automation giants join users and others in a renewed open automation journey to create fully open automation that will plug and play.

Stone Shi is executive editor-in-chief of Control Engineering China. Edited by Mark T. Hoske, content manager, Control Engineering, CFE Media and Technology,

KEYWORDS: Open automation, interoperability, IEC 61499


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Author Bio: Executive editor-in-chief, Control Engineering China