PLC hardware speed, I/O, communications, redundancy, Part 1: PLC introduction, evolution

Programmable logic controller (PLC) insights

• In a November 9 webcast, “PLC series: PLC hardware speed, I/O, communications, redundancy,” David Ubert, senior automation specialist at Black and Veatch, and Eelco van der Wal, managing director at PLCopen, discussed how PLC designs have changed to meet automation and control challenges in recent years.
• In Part 1, Ubert discusses the evolution of PLCs, and their diverse applications.

In the ever-evolving field of industrial automation, programmable logic controllers (PLCs) have been a mainstay, adapting to the changing needs of various automation applications. Known for their robustness and versatility, PLCs remain a preferred choice for machine control, motion control, and even certain process control applications. However, as the demands of modern automation grow increasingly complex, it’s essential to understand where PLCs fit best in today’s industrial landscape.

In a November 9 webcast, “PLC series: PLC hardware speed, I/O, communications, redundancy,” David Ubert, senior automation specialist at Black and Veatch, and Eelco van der Wal, managing director at PLCopen, discussed scenarios where PLCs are most effective, how their designs have changed to meet contemporary automation challenges, and what key criteria end-users should pay attention to when selecting PLCs for specific applications.

The transcript of their presentation has been provided with minor edits and adaptations.

Introduction to programmable logic controllers (PLCs)

David Ubert: Today, I am excited to discuss programmable logic controllers (PLCs), focusing on their hardware speed and communication systems. Throughout my career, I have extensively worked with PLCs. To begin, I’ll cover some basic concepts. Recognizing the diverse audience, it’s important to start with a brief overview of PLCs’ origin. PLCs emerged in the late 1960s and early 1970s, predominantly in the automotive industry, which significantly drove their development. The industry aimed to replace traditional relays with more advanced and efficient technology, enhancing their competitive edge.

Evolution and applications of PLCs

An interesting aspect of this evolution is the initial goal to replace relays with PLCs. Despite this, even today, relays maintain a high current rating on contacts, a feature less common in PLCs. However, PLCs have been improving substantially in this regard. It’s common to see PLC panels incorporating isolation relays, serving specific purposes.

Technology, inherently, is fascinating, especially considering its non-linear progression. Technological advancement is indeed exponential. Reflecting on history, for thousands of years, transportation relied on camels, horses, and buggies. However, within a relatively short span – from the invention of the automobile in 1885 to landing a man on the moon less than 90 years later – technology has rapidly advanced. This exponential growth makes the field exhilarating for professionals like myself. Embracing new technology leads to innovative ideas and even more advanced technologies, as evidenced in the ongoing development of PLCs.

The importance of keeping up with technological advancements

It’s crucial to stay abreast of technological advancements. I’ve encountered clients hesitant to adopt new technologies due to fear of unfamiliarity, potential malfunctions, or lack of understanding. However, it’s imperative to grow with technology and be a part of its evolution. PLCs are utilized across various industries. For example, the power sector heavily relies on PLC and networking equipment, given its critical nature. Water and wastewater management is another significant area where I have considerable experience. These facilities extensively use control and PLC systems.

Diverse applications of PLCs in industry

Industries like Frito-Lay, Coca-Cola, Pepsi, and even the space program regularly employ PLCs. My experience includes programming and designing numerous PLC systems. While jokingly saying, “We’re not launching the Space Shuttle here with this PLC,” the reality is that it’s possible due to their versatility. PLCs have a wide range of applications, from communication systems to batching systems. For instance, on the screen’s left side, a palletizer, typically featuring a robotic arm, moves materials between conveyors and locations, exemplifying a perfect PLC application. At the screen’s center top, you see a typical batching system, involving transferring and mixing substances in tanks to produce a final product – another excellent application for PLCs. Lastly, humorously, while a PLC might be overkill for a home sump pump, as shown on the right side, it illustrates the potential for PLCs in various applications.

Different manufacturers offer a variety of PLCs, each with unique platforms. These platforms vary in size, with some designed for extensive input/output (IO) handling, while others manage minimal IO. This diversity caters to a wide range of applications. Additionally, certain industries, like pulp and paper or the steel industry, require high-speed applications. Historically, these needs were addressed by Distributed Control Systems (DCS), leading to a debate over the superiority of DCS systems compared to PLCs. A DCS system, placing control at required locations, has historically been equipped with high-speed networks, making it ideal for such applications.

Do you have experience and expertise with the topics mentioned in this content? You should consider contributing to our WTWH Media editorial team and getting the recognition you and your company deserve. Click here to start this process.