PLCs and other controllers in an IIoT world: More answers

Industrial Internet of Things (IIoT), Industry 4.0 and smart manufacturing concepts are familiar to architects of industrial automation and controls. How are programmable logic controllers (PLCs) and industrial PCs (IPCs), embedded controllers, programmable automation controllers (PACs), smart input/output (I/O) modules, other logic devices and related software helping IIoT implementations. Kevin Gibson, senior controls engineer, Applied Manufacturing Technologies (AMT) and L. John Shipley, PE, CAP, director of Indiana operations, senior electrical engineer, Patti Engineering, provide answers in a Nov. 11 Control Engineering webcast, “PLCs and other controllers in an IIoT world,” archived for a year, thereafter. An RCEP professional development hour is available.

Below, see additional answers from the webcast’s question-and-answer session.

PLC versus relay, other controllers, cybersecurity, low-cost PLCs

Question: I get that one could set up a smart input device to “publish” a value or a signal directly to a cloud service, but what’s wrong with just having the PLC relay the value or signal up through the traditional layers?

Shipley: It takes a great deal of work and engineering to get the devices and systems at each layer to share data. A single data point to a single cloud service would require the PLC to collect the data point’s value from the device, prep and process the value to send to a supervisory control and data acquisition (SCADA) system or manufacturing execution system (MES), the SCADA or MES would need to have a transaction with an enterprise resource planning (ERP) system which in turn would need to share the data point’s value to a cloud service via a database transaction.

If the device could skip all those other systems and publish the value directly to the cloud service that needs the value, then less work would be needed to set it up. Additionally, various metadata might be needed and/or appended to the data point’s value for the value to be handled up through the various layers and then ultimately discarded at the final point. This would be extra work and extra memory that otherwise could have been avoided.

John Shipley, PE, CAP, director of Indiana operations, senior electrical engineer, Patti Engineering, (right) was in the Nov. 11 Control Engineering webcast, “PLCs and other controllers in an IIoT world,” archived for a year, thereafter. An RCEP professional development hour is available. Also presenting in the webcast is Kevin Gibson, senior controls engineer, Applied Manufacturing Technologies (AMT). Courtesy: Patti Engineering, AMT, Control Engineering

Question: We’ve always used PLCs, but are considering other controllers for a few applications. Any tips?

Shipley: I recommend starting by determining your application requirements. Ask these questions.

• What will the controller be controlling?
• How much memory is needed?
• What devices/systems will your controller need to interact with?
• What communication medias will be needed?
• What communication protocols should be used to assist in communicating to those other devices/systems?
• What is your budget?
• What is your plan to support the controller throughout the ownership period?

Also make sure to consider likely expansion needs to accommodate future improvements. From there your requirements should eliminate many alternatives and leave a set of possible controllers to consider.

Question: Is there one place to look for all controller cybersecurity vulnerabilities, or do I need to look at each manufacturer’s website?

Shipley: A manufacturer’s website is a good place to look for solutions to handle known vulnerabilities.

The U.S. government agency Cybersecurity & Infrastructure Security Agency (CISA) regularly issues alerts about known vulnerabilities under the Industrial Control Systems alert system (ICS-CERT). These alerts can be viewed by vendors as well.

Question: Are low-cost [under $100] PLCs a good replacement for embedded and PLC controllers?      

Shipley: It could be depending on the controller and application. Such a very low-cost PLC is closer to the total cost of an embedded controller package. Micro PLCs may lack some of the cloud connecting capability that we mentioned earlier in the webcast but as a low-cost controller without developing something inhouse, from scratch, and employing electronic engineers, low-cost options may help a new original equipment manufacturer (OEM) or an established OEM developing a new product.

More on these topics is available in the 1-hour webcast and question-and-answer session that’s part of the on-demand webcast. Browse all on-demand webcasts here: www.controleng.com/webcasts/past.

John Shipley, PE, CAP, is director of Indiana operations, senior electrical engineer, Patti Engineering; edited by Mark T. Hoske, content manager, Control Engineering, CFE Media and Technology, mhoske@cfemedia.com.

KEYWORDS: Controllers, PLCs, IIoT, Industry 4.0

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