The Programmable Logic Controller (PLC) has become an essential component in the factory automation and process control space. PLC is a digitally operating electronic system that uses a programmable memory for the internal storage of user-oriented instructions to execute specific functions such as logic, sequencing, timing, counting, and arithmetic. In addition, PLC uses both digital and analogue inputs and outputs (I/O) to control various types of machines or processes.
In 1968, when General Motors wanted to replace the hard-wired relay system of assembly lines with one that could be controlled electronically, for performing basic arithmetic operations and printer control, the company was determined not to replace the schematic diagram-based programming, i.e., the ladder logic programming. The reasoning behind such a step was that operators required only a little time to train and execute a ladder logic program. With advances in both hardware and software, PLCs can now be operated through almost any programming language. However, to maintain interoperability, the International Electrotechnical Commission (IEC) developed an open international standard, IEC 61131-3, which standardized five PLC programming languages.
- Ladder Diagram
- Function Block Diagram
- Structured Text
- Instruction List
- Sequential Function Chart
Similarly, PLC form-factors have undergone rapid changes since their introduction. The hardware component of PLCs have evolved from being a simple I/O controller to a microprocessor-based unit and then to a more advanced unit with intelligent I/O modules for machine positioning and control. Today, PLCs come in many forms such as mini-PLCs, nano-PLCs, and PC-based Programmable Automation Controllers (PAC); they serve multiple utilities such as discrete control functionality, motion control, and Human Machine Interface (HMI).
The increasing demand for advanced features, interoperability, and cost-effectiveness have driven PLC vendors to innovate rapidly and integrate conventional PLCs with modern and contemporary technologies. However, customers still face an array of challenges for any plant. One of the most common challenges is the presence of multiple PLCs in a single plant. This results in complex integration of systems and high costs of maintenance. Often, multiple PLCs will not have a single owner but will be managed by multiple vendors such as engineering, procurement, and construction (EPC), original equipment manufacturers (OEMs), or PLC vendors themselves. This results in many disorientations and discrepancies in the standard operating procedure (SOP) of a PLC system. Poor connectivity between the assets is another issue faced by end-users, who find it challenging to capture data from proprietary protocols. This in turn decreases the quality of visualization and increases downtime, owing to delayed service leads. Finally, the most crucial challenge faced by the customers is the cybersecurity risk.
Most often, concerns over cybersecurity drive customers to invest a large amount of capital on insurance. Thus, all these challenges demand the need for a robust PLC solution, which has a standardized approach, engineering flexibility, and secure connectivity.
The development of a PLC that offers high-performance enhanced control, and secured connectivity has led major PLC manufacturers to rely on Industrial Internet of Things (IIoT) technologies, such as smart sensors, Machine-to-Machine (M2M) communication, industrial cloud, and cybersecurity. However, IIoT-ready PLCs face new types of challenges, thereby creating a need to redesign the whole PLC from the ground up.
PLC developers are adopting the smartphone approach to design modern-day PLCs. This requires the replacement of conventional PLC processors with system-on-chip (SoC) processors. Some well-known examples of SoCs in the smartphone market are Qualcomm’s Snapdragon, NVIDIA’s Tegra, and Intel’s Medfield. These SoCs carry a microprocessor with advanced components, such as a graphics processing unit (GPU), software modules, and Wi-Fi. In the industrial domain, such SoCs have to offer the capabilities of both microprocessor and field-programmable gate array (FPGA), so as to run the control software coupled with the master communication protocol stack. The rapid innovation in SoCs and their capabilities has enabled PLC vendors to accelerate new product development and reduce the time-to-market.
Multinational technology companies have identified vast potential in the PLC market by developing new-generation technologies to enable PLC vendors to provide better products. One such example is Intel Corporation’s (Intel) Alter SoC for PLCs. Alter collaborated with 3 companies, viz., 3S-Smart Software Solutions GmbH, EXOR International, and Barco-Silex to develop the SoC, which could support the integration of HMI and secure connectivity over Open Platform Communication Unified Architecture (OPC-UA). Furthermore, Alter’s chip has a secure sockets layer (SSL) encryption in the FPGA, which makes it four times faster than conventional processor-based implementation. PLCs that have Alter’s chip can seamlessly connect to the cloud through secure M2M connections. Such advanced capabilities in a single chip enable PLC vendors to focus more on developing customer-centric and application-centric PLCs, than on developing new processors for the product.
The key takeaway from Intel’s foray into SoCs for PLCs is that technology companies have recognized the market and technological gaps in the PLC market, and are developing proprietary solutions, which not only provide PLC vendors with innovative tools but also empower end-users with the power of IIoT. Furthermore, strategic partnerships with companies that have unique expertise, such as PLC software development, HMI development, and cybersecurity, have enabled Intel to create the most advanced chipset for PLCs. As a result, the PLC market has increasingly witnessed the penetration of non-traditional industrial participants that are completely transforming the way a PLC is designed, manufactured, and deployed.
The different technologies of IIoT have enhanced the basic functionality of a PLC, either by connecting it to the cloud or by generating actionable insights from collected data. Since the advent of IIoT, the one unending speculation of the industry observers and manufacturing industry stakeholders is, if PLCs will become obsolete. According to Frost & Sullivan’s latest report on this market, entitled “Strategic Analysis of the Global PLC Market”, PLCs will certainly undergo changes in form-factors and software programming; however, the fundamental value that a PLC offers is far from changing and will continue to prevail till the need for controlling an application persists.
