In a Tech Update feature headlined “PLCs and contgrollers are being used as intelligent gateways to IIoT,” we looked at programmable controllers (PLCs), programmable automation controllers (PACs) and to some extent industrial PCs (IPCs), the latter of which can certainly be applied to most any level of control—e.g., discrete, PID, batch, etc. We considered new functionality in today’s controllers, internal operating systems, I/O capabilities, security and networking—both at the fieldbus/controls level (OT) and IT-side connections.

I intentionally didn’t spend a lot of time on PLCs/PACs and their role in IIoT networks for a couple of reasons. First, we covered IIoT in great detail in the January issue of FE, “The connected food plant of the future will be a lean information machine,” and in the July issue, we focused on “How food processors can use IIOT for maintenance activities.” Second, I wanted to spend time looking specifically at controller and I/O functionality—not IIoT—though we tangentially touched on IIoT. With these two articles, I felt like I wrote a book on IIoT, and I’m grateful for all those who provided input on the subject.

Does IIoT belong in a discussion on PLCs, IPCs and PACs?

In fact, when I considered interview questions for the PLC/PAC article, I wondered if indeed I should’ve even considered asking the experts a question concerning the role of PLCs and PACs in an IIoT environment—as I thought the answer was intuitively obvious, redundant or didn’t relate to the subject at hand…or maybe all three.

So, the question I posed to my interviewees went like this: I’ve tried to avoid the term “IIoT” as I think the modern PLC/IPC or PAC is just one tool/device that fits into an overall networked strategy. What do you think? Can we have this discussion on PLCs and PACs without using the term “IIoT”?

Well, I got a multitude of responses to the two questions.

IIoT has been presented as something really new by network suppliers and members of the technical/trade press, but when you get down to the nitty-gritty, is IIoT really a new concept? Nate Kay, project manager at MartinCSI, a Certified Member of the Control System Integrators Association (CSIA) says, “It’s just adopting technologies that we already use in everyday life and applying them into the industrial space.”

In fact, Jack Gourley, Tri-Cities regional engineering manager at Concept Systems (a CSIA member), thought I didn’t need to devote a lot of time to IIoT in a PLC/PAC article. “Industrial internet of things implies connecting devices to the internet; it’s not specific to what the controls are doing. IIoT is speaking very generally. I don’t think you need to mention IIoT.”

PLCs first on the scene—but you can’t ignore IIoT

“In my opinion, for the industrial world, data collection and analysis (two of the primary benefits of the IIoT) have always been important, and PLCs have often been the tool utilized to perform these functions,” says Bill Dehner, AutomationDirect technical marketer. “Even before Ethernet communication (which facilitated the IIoT), PLCs were collecting data and helping improve processes and system performance. For as long as I have been in automation, production data and analysis has been vital for industries trying to stay competitive, and many industries have been reaping the benefits of data collection long before the term IIoT ever surfaced.”

Predictive maintenance is a big reason for data collection and while the IIoT does have its benefits, the PLC has been providing these core benefits for decades, adds Dehner. “Therefore, I believe you can have a PLC discussion without using the term IIoT, but it may be far harder to have a discussion of the IIoT at this moment in time without mentioning the PLC.”

There is certainly a lot to think about and consider outside of the IIoT discussion, says Allen Tubbs, product manager for Bosch Rexroth—Automation & Electrification Solutions. “Operational Technology will always have a different way of doing things when compared to Information Technology. There are real concerns to address regarding safety, integration efficiency and feature sets for machine controls that take consideration. But that IIoT elephant in the room is growing and at some point, especially in new control specifications, it has to be given its time, too, or you will regret it later.”

“I agree that the modern PLC/PAC is just one tool or device that fits into the overall networked strategy,” says Arun Sinha, Opto 22 director of business development. IIoT, though, is a hard term to avoid in today's discussions because many of the advancements in modern PLCs are intended as IIoT-enabling technology, such as new IT-friendly communication protocols and data formats, RESTful APIs, edge computing capabilities, etc, says Sinha.

But there are indeed advancements in PLCs/PACs today that serve more traditional applications, continues Sinha. A few examples in the groov EPIC (edge programmable industrial controller) include things like the integral high-resolution color touchscreen for configuration and troubleshooting, several programming options, OPC UA on board the controller (via Ignition Edge), an on-board, mobile-ready HMI—and the ability to run a database in the controller—to name just a few.

While we’re talking about “edge” controllers—devices that have the ability to push data into the cloud from a process—we’re seeing suppliers coming up with specific designs to handle this specific application.

PLCs/PACs are both the edge and the foundation of the industrial process, says Vibhoosh Gupta, Emerson senior product manager. They are the edge because they are the closest to the process or industrial asset (machine).

“This is why Emerson has created a new class of controllers called Outcoming Optimizing Controllers (OOC) that can not only do real-time deterministic controls but can provide the ability to improve or optimize the process by running analytics or providing business guidance from a variety of sources to the process in a safe and cooperative manner,” says Gupta.

Options, options and more options with IIoT connected devices

Automation engineers today have more options and flexibility than they’ve ever had when it comes to “where” to run their programs and computations to process data, says Jim Wilmot, marketing manager, SIMATIC PLC, I/O, Software, Siemens/Digital Industries – Factory Automation.

With the advent of IIoT gateways, this can be done now not only in the PLC, but also on edge devices, or even in the cloud, etc., adds Wilmot. Even with all the new high tech options available, a large number of applications are handled easily with a standard PLC, which will always have a place moving forward. The term “PLC/PAC” sometimes brings a vision of a very basic device for handling simple I/O processes, which is definitely not the case with today’s more technically advanced PLCs. The truth is that today’s PLC/PACs have extremely powerful communications built onboard, cloud connectivity onboard, and digital simulation capabilities, which make them a critical component in IIoT ecosystems moving forward.

“IIoT frequently involves cloud connectivity, and Beckhoff IPCs are inherently capable of acting as IoT gateways or edge computing devices,” says Eric Reiner, industrial PC product manager for Beckhoff Automation LLC. There are multiple ways for machines to connect to higher-level systems, whether private clouds or enterprise level plant networks. Cloud connectivity promises great benefits for food processing and packaging machines; however, many still operate successfully as islands of automation. Flexible IPCs contribute to success with any level of connectivity. PC-based machine controllers can provide significant data acquisition and analytics capabilities locally via TwinCAT 3 automation software, as well as machine learning and other functionality typically associated with IIoT. Cloud connectivity is not a prerequisite to using advanced algorithms to enhance efficiency, performance and machine health with IPCs. This is not the case with traditional PLCs and PACs.

Connecting islands of automation and diverse protocols

The overall advantage of PC-based machine controllers is that systems originally implemented as islands of automation don’t have to be stranded forever, adds Reiner. These machines with legacy fieldbuses can easily become cloud connected in the future with the addition of small pieces of hardware and software. As a result, food processing equipment can readily evolve to support an operation’s evolving IIoT strategy.

However, with all the legacy fieldbuses and possible connections, there are still problems communicating—and this is where everybody needs to talk. “Although connectivity has been available in most PLCs for at least two decades, nowadays it’s important to have a conversation between vendors, machine builders and users about standardizing communication protocols and even some libraries,” says Sandro Quintero, Festo Corporation product marketing manager – Electric Automation.

“This is the reason why protocols such as IO-Link and OPC-UA are gaining a lot of traction in the present,” says Quintero. The next step will be to define what to do with all the data generated. Are vendors going to provide diagnostic libraries for their devices? This is also an opportunity for machine builders to offer additional features such as predictive maintenance and diagnosis.

In an effort to standardize on machine/automation communications and IIoT protocols, Schneider Electric recently launched a new Modicon M262 IIoT-ready controller for logic and motion applications. It offers intuitive, scalable and reliable machine integration into Industry 4.0 environment, and machine-to-device, machine-to-human, machine-to-machine, machine-to-plant or machine directly-to-cloud connectivity. The controller embeds cybersecurity features and encryption protocols to provide direct cloud connectivity and digital services thanks to its two ready-to-work and independent embedded Ethernet ports.

And to help with some of the communications issues that many systems have—as Quintero described—the controller provides integration into the plant with open protocols, including OPC UA, PackML, SQL or integrate to the cloud with MQTT, JSON or HTTPs requests (API).

“With Modicon M262, we have a new EcoStruxure Machine where OEMs can gain real-time remote access to their machines using EcoStruxure Machine Advisor, allowing them to modify and add new services to each installed machine at any production site worldwide,” says Carlos Villa, vice president–industry US, Schneider Electric. “This new EcoStruxure offer further differentiates our OEM partners who are making this analytics service available and offers additional value to their end user customers who benefit from this operational insight.”

Read the original FE October 2019 Tech Update article, “PLCs and contgrollers are being used as intelligent gateways to IIoT,” on line.


For more information:


Beckhoff automation LLC,

Bosch Rexroth—Automation & Electrification Solutions,

Concept Systems,


Festo Corporation,


Opto 22,

Schneider Electric, M262 controller

Siemens / Digital Industries – Factory Automation,