What Industry 4.0 means for PLCs

Meeting the Next Industrial Revolution with pervasive sensing, distributed control, and robust, seamless connectivity.

Industry 4.0 is creating new opportunities in the equipment market, as manufacturers transition from traditional programmable logic controllers (PLCs) to Micro PLCs and Embedded PLCs. In this white paper Suhel discusses new strategies to meet customer demands for more functionality in less space.

In today’s highly competitive global economy, small improvements in manufacturing processes can yield huge competitive advantages.

This mindset is driving fundamental transformations across the factory floor. Manufacturers are deploying the latest sensor technologies, adopting new control architectures, and starting to discover the potential of “big data” and analytics. Often called Industry 4.0, what’s happening in manufacturing is nothing short of a revolution.

For equipment OEMs, this represents a massive opportunity. The number of sensors used to track environmental and process variables continues to increase. This is accelerating the transition to a distributed control architecture, as plant operators seek to reduce bottlenecks and shorten control loops by moving PLCs closer to the processes they control. Ultimately, the promise of improved operational efficiencies and yields will lead to the largest overhaul of plant operations since the invention of the PLC. This poses a considerable challenge for PLC engineers.

To win in this market, system designers will need to pack more I/O and more functionality into enclosures that keep getting smaller. The problem is that there’s relatively little space to be gained from digital scaling of the microprocessor. In today’s advanced PLC modules, analog and discrete components consume approximately 85% of board space.

Engineers can no longer afford to ignore the obvious problem on their boards. Many of the analog and discrete components that have worked so well in previous systems are simply too big for Micro PLCs and embedded controllers. The promise of Industry 4.0 will only be realized through greater levels of integration, across the PLC system design.

The Next Industrial Revolution Has Arrived

 Thanks to the digital revolution, PLCs have become progressively more powerful over the years.

PLCs have been at the nexus of industrial transformation ever since the introduction of the Modicon 084 in 1969. Thanks to the digital revolution, they have become progressively more powerful over the years, capable of handling more inputs, larger words, and more complex instruction sets.

Today, innovations in analog and sensor technology are helping manufacturers take full advantage of the massive compute resources available, both within the factory and in the cloud. Industry 4.0 represents a vision for what’s possible when you combine this intelligence with pervasive sensing, distributed control, and robust, seamless connectivity.

And once again, the PLC finds itself at the center of a revolution. This is creating new business opportunities for PLC OEMs as manufacturers increase capital expenditures to take advantage of these technologies.

However, it also raises a variety of challenges for system designers.

 

Realizing the Promise of Big Data

Thanks to the steady march of Moore’s Law, we now have massive amounts of processing power at our disposal. This enables enterprises to crunch terabytes or even petabytes of data to enhance decision making, generate new insights, and optimize processes.

For manufacturers, the biggest challenge is collecting and acting on this data. Three technology trends have emerged to address this problem:

• Pervasive Sensing. The cost of sensors and their interfaces continues to decline, enabling manufacturers to track more variables and types of data.
• Distributed Control. Moving process controllers closer to the machines they control eliminates bottlenecks to improve manufacturing throughput and flexibility.
• Seamless Connectivity. Manufacturers are connecting the factory floor to the enterprise network to unlock the potential of big data and analytics. This brings numerous benefits, but it also raises many security issues at the system level.

Addressing the New Integration Problem

The biggest problem in PLCs is the one that no one sees. A recent market study revealed that most engineers still believe that digital technology offers the best opportunity for spacing savings. Yet, digital chips consume just 15% to 20% of the board space in PLC modules.

The real problem is the amount of PCB devoted to analog and discrete components. These devices consume as much as 85% of available board space in PLC modules (Figure 3). But they don’t scale like digital chips, so greater levels of integration are needed to conserve PCB space while delivering the required functionality.

Solving this problem requires a new approach to analog design. Gone are the days when system designers could just select catalogue parts with adequate specs and then perform heroic feats in layout to make them fit the PLC enclosure.

Today’s market requires a step-function improvement in space and energy efficiency. To be successful designers will need to systematically look for opportunities to streamline analog circuitry and reduce power dissipation.

Fortunately, new solutions are being developed by companies, such as Maxim Integrated, who are looking to capitalize on their integration capabilities as the industrial market evolves. Combining multiple discrete functions in a single IC can provide system designers with significant advantages in size, power consumption, and cost.

Today’s market requires a step-function improvement in space and energy efficiency.

Maxim’s Micro-PLC Technology Demonstration Platform shows how analog integration can enable a 10x smaller PLC footprint, 50% cooler operation, and 70x faster throughput for digital I/O (Figure 4). These achievements are realized using Maxim’s Smart Integration approach to product development and our proprietary process technology.

Increasing I/O Density in Micro PLCs

I/O are the essential link between PLCs and the countless sensors and actuators required by Industry

4.0. As manufacturers add more sensors across factory floors, equipment designers must push channel density ever higher, even as available space in the PLC continues to shrink.

Combining multiple discrete analog functions in a single IC can provide system designers with significant advantages in size, power consumption, and cost.

The I/O isolation architecture offers an opportunity for significant space savings. The traditional approach is to use one optocoupler per channel, connecting each optocoupler output to a digital input on the microcontroller. This approach is costly in parts count, board space, and use of digital I/O pins.

Today, multichannel serializers like the MAX31911 can translate, condition, and serialize the 24V digital outputs of sensors and switches to the 5V, CMOS-compatible levels required by PLC microcontrollers. This approach can reduce the necessary number of isolated channels to just three.

The MAX31911, for example, is an eight-channel industrial interface (Figure 5) that supports SPI daisy chaining, so larger numbers of inputs from multiple serializers can share the same three isolated signals.

Figure 6 shows the dramatic savings in power dissipation, parts count, overall PCB real-estate footprint,

optocouplers, and cost for a 32-channel implementation, compared to the nonserialized approach.

Lowering Heat Dissipation in Power Designs

Higher I/O density and smaller form factors also add to the design challenge in another basic way, a consequence of the inevitable power dissipation. The system must be more power efficient than ever to keep the PLC from overheating, especially in an application where fans and vents are generally not acceptable.

An often-overlooked source of heat in PLCs is I2R losses in the DC power-distribution feeds. Frequently, 24V is used for PLC backplanes, while 12V is used for on-board distribution. A better approach is to use 48V across the board, as this reduces currents by a factor of 4 and, correspondingly, PCB copper losses by a factor of 16.

Using high-voltage point-of-load DC-DC converters like the MAX17503 eliminates the need for an intermediate DC-DC conversion stage. These converters operate directly with up to 60V inputs to enable single-stage conversion for digital, analog, and mixed-signal loads at low voltage, freeing valuable board space while avoiding the cost and energy losses of the interstitial stage. Additionally, they minimize copper losses, reduce connector contact current ratings, and increase reliability while maintaining cool operation (typically 50% cooler) due to their synchronous switch architecture (Figure 7).

Reducing the Complexity of Power Subsystems

Today’s signal-conditioning, processing, and communication circuits require a diverse set of power rails, often differing by a few volts or only fractions of a volt. This exacerbates an already complex electrical environment. Add to this the increasingly sophisticated methods of energy savings through various power-control methods, and the cost and complexity of power subsystems only increase further.

Maxim’s Beyond the Rails products simplify the signal chain, enabling a design (Figure 8) that allows ±10V bipolar inputs to be multiplexed, amplified, filtered, and digitized, all with a single 5V supply. This eliminates the need for additional ±15V power supplies, thus reducing component count, system cost, power dissipation, and footprint.

Integrating Safeguards Against New Security Threats

When factory networks were closed to the outside, IT security issues usually involved rogue employees and internal data theft. Those “good old days” are gone, and are not coming back. Today’s Internet-connected PLCs must be protected against multiple threats, including hackers, malware, and viruses.

Today’s Internetconnected PLCs must be protected against multiple threats, including hackers, malware, and viruses.

System-level software provides an initial level of protection, but in many cases this isn’t enough.

Hardware-based security is needed to protect against:

• “Cloned” or counterfeit components. Counterfeit field sensors and I/O modules pose a real threat to your bottom line, but the bigger danger is that they could be used to execute an attack on the industrial environment. Using a secure authentication IC is the only way to guarantee that you can trust the temperature readings being sent from a boiler and other critical components.
• Malware injection. Stuxnet was a wake-up call to industry. System operators must ensure that all equipment upon which a SCADA or DCS system is built runs genuine software. Secure boot and secure update management are the best ways to protect a device from malware injection. A secure coprocessor

can be used to implement an encryption design that fully addresses these issues with minimal design-in effort.

• Eavesdropping. As concern over industrial espionage increases, manufacturers must ensure that unauthorized users cannot steal trade secrets off of industrial networks. Encryption and authentication ICs can protect against such eavesdropping, and go further with active tamper detection to prevent brute-force attacks on the hardware components.

Maxim has a rich history in hardware security implementation for ATMs, POS systems, and consumables such as printer cartridges. Our security product portfolio ranges from simple authentication engines to complex secure microcontrollers that can implement advanced standards-based encryption algorithms.

Seize the Integration Advantage in PLCs

Industry 4.0 is fundamentally transforming what it takes to win in the PLC market. Smaller form factors, higher

I/O density, and advanced capabilities—success today necessitates new strategies for managing competing demands for more functions in less space.

This problem will not be solved by Moore’s law. The large amount of analog content in these systems means that PLC engineers can no longer afford to ignore the integration problem in front of them. Not when success depends on how much functionality you can pack into every centimeter of space. Engineers who systematically seek out higher levels of component integration will be well positioned as manufacturers pursue the benefits promised by Industry 4.0.

At Maxim Integrated, we’re building on our legacy for great industrial products like the MAX232, and developing a range of solutions that specifically address the integration challenges raised by Industry 4.0.

Explore Our Solutions

Transform analog into your biggest competitive advantage with Maxim Integrated:

maximintegrated.com/Industrial-Integration

About the Author

Suhel is a Sr. Principal MTS in charge of Control & Automation segment strategy at Maxim Integrated.

Prior to joining Maxim, he led the industrial automation segment marketing at Altera Corp. Suhel has over 20 years of product/segment marketing experience in various Silicon Valley companies such as Xilinx, Altera, and Tabula.

He has published numerous articles and is an author of the book “Digital Video Processing for Engineers.”

Suhel holds MSEE and MBA degrees from Arizona State University and a Graduate Certificate in Management Science from Stanford.