Key Highlights
- The future of PLCs is increasingly data-centric and protocol-flexible, driven by edge computing and Industry 4.0 demands, though engineers must still weigh performance, cost, reliability and standards such as SIL before adopting next-generation controllers.
- Yokogawa Electric’s OpreX Intelligent Edge Controller A8 reflects a broader shift toward Linux-based, AI-ready edge controllers that merge PLC, IPC and data-platform capabilities into a single device.
- Networking flexibility, including native support for standards like Profinet, EtherCAT, MQTT and OPC UA, is becoming as important as deterministic real-time performance in modern controller selection.
Yokogawa has released the OpreX Intelligent Edge Controller A8. Americans were sleeping. “What is that?” you ask. “Just another controller?” Not exactly. Is there a new generation of programmable logic controllers (PLCs) emerging?
The OpreX is another example of traditional distributed control system (DCS) businesses expanding their lines of products to encourage a new generation of PLCs and PLC thinking. The OpreX is a Linux-based edge controller plus a data platform.
What is it good at? The OpreX is manufactured for real-time deterministic control and data-centric architectures, and it is AI-ready. It’s designed to reduce development time. It combines the PLC, industrial-PC (IPC) and edge-computer roles into a single device.
Yokogawa is targeting the chip-making industry for this new controller. How does the OpreX compare to others? Yokogawa OpreX A8 is an edge controller class PLC. Siemens’ Simatic S7-1500 and Rockwell Automation’s ControlLogix are classic PLCs. Beckhoff’s CX series of embedded PCs is an industrial PC/PLC hybrid. PLCnext merges PLC functionality with high-level programming in an open ecosystem for customization. They are all reliable. They are all real-time deterministic platforms.
Operating system
The OpreX A8 is using Linux with real-time extensions. The computer model is PLC plus edge for data handling. Virtualization is possible. Artificial intelligence and machine learning (ML) are built in with native support.
Other platforms might have a PLC operating system and no virtualization, with AI and ML as external add-ons to the controllers. Some can run AI/ML via Windows.
Programming environment
Traditional platforms are utilizing IEC 61131-3 standards for PLC languages. There is a dividing line between the platforms in regard to higher-level languages. Python, C/C++, .NET and Linux applications are easily interfaced with OpreX A8, Beckhoff CX, and PLCnext, if you are familiar with the nuances of their environments and can access the application ecosystems.
Fieldbus and networking
Yokogawa, S7-500, Beckhoff and PLCnext all have Profinet as an inherent interface. ControlLogix allows Profinet with additional hardware. Flip that for Siemens when considering Ethernet IP protocols. Beckhoff has EtherCAT standard, and PLCnext will allow EtherCAT add-ons. Message queuing telemetry transport (MQTT) is native for most of the non-traditional PLCs. OPC-UA is still the No. 1 interface for merging platforms.
Real-time performance
OpreX A8 is comparable to other platforms, but Beckhoff and Siemens still have the fastest high-speed loops for motion. This is something to think about when specifying an edge controller as opposed to a traditional PLC.
If the edge controller does data and real-time processing, where is its memory allocated?
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Beckhoff allows you to split the memory the way you want, so it adds flexibility, but a controls person must think about what the application is doing. Do you need all that data processing in the field?
Again, using traditional engineering standards and defining the application is the best way to choose these products. Performance is one factor to consider. Cost and reliability are also factors to consider.
The PLC future
Reliability is still in the classics, but Yokogawa has a long lifecycle. Its novelty might hold the OpreX A8 back a bit since controls engineers are finicky. They will have to get used to it. Upon its release, OpreX A8 does not currently have a safety integrity level (SIL) rating.
The takeaway should be that the PLC is changing. In the past five to 10 years, the push has been faster, smarter and easier to interface. One key thing is to not be protocol-dependent, even though one must get excited when MQTT is native to a machine.
The other key thing is the ability to program without having to break the bank or learn specific languages. The drive for this is the data exchange in the field.
What is interesting is that a large company like Yokogawa is listening and spending the time and money to brand a new PLC. This means all the hype about Industry 4.0 has some merit, because it has instigated change. The edge computing trend for PLCs magnifies this. Also, newer PLCs have more concerns about data, data storage and data transfer than before.
It is hard to answer the question of whether a new generation of PLC is emerging. However, it is evident that manufacturers are wanting the PLC to be more adaptable to data needs and to be easily programmed, while not being restrained by specific operating systems or protocols. Stay tuned while the PLC and industrial control systems keep evolving.
About the Author
Tobey Strauch
Arconic Davenport
Tobey Strauch is currently managing brownfield installations for controls upgrades at Arconic Davenport. She has previously worked as principal controls engineer and before getting her bachelor’s in electrical engineering, was a telecommunications network technician. She has 20 plus years in automation and controls. She has commissioned systems, programmed PLCs and robots, and SCADAs, as well as managed maintenance crews. She has a broad mix of mechatronics with process control. She enjoys solving problems with Matlab and Simscape. Contact her at [email protected].
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