Exposing the Secrets of PLC Programming Myths!

In today’s rapidly evolving world of manufacturing and automation, it’s essential to understand how Programmable Logic Controllers (PLCs) operate. However, many common misconceptions about PLCs can create confusion. We will clarify five widespread myths about PLCs, focusing on their unique functions, programming challenges, and the need for a thorough approach to their use.

By addressing these myths, we can gain a deeper understanding of how PLCs enhance efficiency and precision in modern manufacturing. Let’s explore the realities of PLCs and discover the facts that highlight their essential role in today’s industry. Continue until the end to clarify a bonus myth.

Myth 1: PLCs and CNCs are the Same

While both Programmable Logic Controllers (PLCs) and Computer Numerical Controls (CNCs) play pivotal roles in the realms of manufacturing and automation, they cater to distinctly different functions and are not interchangeable.

PLCs are sophisticated systems engineered to control and automate a wide range of industrial processes. They excel at managing a variety of inputs and outputs, orchestrating the seamless collaboration of numerous components within a production environment. These versatile controllers are frequently employed in assembly lines, where they monitor and regulate the flow of operations, ensuring efficiency and consistent performance. Their applications extend to complex process control and general industrial automation, making them indispensable for maintaining smooth and coordinated workflows.

On the other hand, CNCs specialize in the meticulous control of machining tools, providing the precise management of movements required to fabricate components with exacting specifications. These systems are integral to modern machining processes, where they translate computer-aided designs into tangible products. By commanding the intricate motions of cutting, drilling, and milling tools, CNCs enable manufacturers to produce high-quality parts with remarkable accuracy, meeting the stringent demands of today’s engineering standards.

Myth 2: PLC Programming is Just Simple, Outdated Ladder Logic

While basic ladder logic can be pretty straightforward for simple tasks, the reality of modern industrial processes often demands more intricate and sophisticated Programmable Logic Controller (PLC) programs. Today’s Programmable Logic Controllers (PLCs) utilize a variety of programming languages, as established by the International Electrotechnical Commission (IEC) 61131-3.

These languages include Structured Text, which resembles conventional programming languages like C or Pascal; Function Block Diagram; Sequential Function Chart; and, of course, the traditional Ladder Diagram.

Ladder logic was developed in the 1960s to facilitate the work of electricians with electrical relays. Even today, it may surprise you that this old method remains popular, despite the availability of new software options, such as Python or C-based systems. Many factories still prefer the traditional ladder style, where the logic is laid out step-by-step.

As industrial applications become increasingly complex, a solid understanding of these various programming languages is more important than ever. This technical knowledge enables engineers and technicians to design and implement advanced solutions that address the specific needs of modern manufacturing and processing environments. Far from being obsolete, Programmable Logic Controllers (PLCs) are continually evolving to meet the demands of industry. They are becoming more integrated with higher-level systems, such as SCADA (Supervisory Control and Data Acquisition) and MES (Manufacturing Execution Systems), enabling improved monitoring, control, and optimization of processes.

Additionally, many modern PLCs incorporate advanced functionalities that enhance their performance and versatility. Their intrinsic reliability and robust ability to function in harsh and challenging environments make PLCs indispensable across a wide range of industries.

Click PLC & AEDES MQTT: What is the Big Deal?

From automotive and pharmaceuticals to food processing and energy, these versatile controllers are critical to ensuring efficient, safe, and consistent operations in diverse applications.

Myth 3: PLC Programming is Just About Coding

One of the biggest misconceptions about PLC (Programmable Logic Controller) programming is that it’s simply about writing code. In reality, it requires a strong understanding of the physical processes being controlled. Here are a few key areas a PLC programmer needs to focus on:

Understanding the Process:

Understand the process - Exposing the Secrets of PLC Programming Myths!

A good PLC programmer needs to know how the machines work. This includes understanding their mechanics, the electrical and hydraulic components, pneumatics (use of gas in systems), and basic physics. Without this knowledge, it’s challenging to create effective programs.

Safety Considerations:

When programming PLCs, safety is crucial. Mistakes can lead to equipment damage, injuries, or even serious accidents. Therefore, it’s essential to test programs thoroughly, follow safety standards (such as SIL ratings), and ensure that strong error management is in place.

Troubleshooting Skills:

Programmers need to be good at identifying and fixing problems that can arise in real-world scenarios. This includes dealing with electrical issues, mechanical failures, and logical errors in the programming.

Successful PLC programming goes far beyond just coding; it requires in-depth knowledge of the machinery and a strong commitment to safety and reliability.

Myth 4: Debugging (Troubleshooting) is Like IT

When debugging Programmable Logic Controllers (PLCs), the process is different from traditional programming. PLCs operate in real time and continuously scan for inputs and outputs. This means you can’t easily pause the system to examine your code without disrupting the ongoing processes.

Scan Time Troubleshooting - Error correction - Debugging

Instead of stopping the execution, debugging requires you to monitor the system while it is running. This often involves monitoring tag values in real-time, understanding how the system’s scan cycles work, and making precise adjustments to the live system. It’s essential to be cautious, as changes made during operation can affect the entire process.

Myth 5: Naming, Comments, and Sound Coding Practices are Not Necessary in PLC Programming

PLC (Programmable Logic Controller) programs are often perceived as simpler and more self-contained compared to other types of programming. This perception can lead some people to believe that adhering to good programming practices—such as using clear naming conventions, providing comments, and employing a modular design—is less critical. However, the truth is quite the opposite. When you overlook these essential practices, your code can become difficult to understand, troubleshoot, and modify.

Exposing the Secrets of PLC Programming Myths!

This challenge becomes even more pronounced if someone else needs to work on the code or if a significant amount of time has passed since you last interacted with it. Neglecting good programming practices can lead to an increase in errors and inefficiencies. If the logic in your program is poorly structured, the likelihood of encountering bugs rises. Additionally, making updates or changes can become a cumbersome task, which slows down the entire process.

Maintaining high standards in your PLC programming not only improves code quality but also enhances the overall efficiency and reliability of the system, benefiting both current and future users.

Bonus Myth: PLCs are Not Vulnerable to External Factors

PLCs are tough, but they can still face several issues:

Electrical Noise/Interference:

Electromagnetic interference (EMI) and radio frequency interference (RFI) can disrupt PLC operations. Good shielding and grounding are essential.

Environmental Factors:

Extreme temperatures, humidity, dust, and corrosive substances can wear down hardware over time.

Power Issues:

Power surges, fluctuations, or outages can corrupt memory or damage components.

I/O Module Failures:

Faulty input/output modules can lead to incorrect readings or malfunctioning devices.

Cybersecurity:

Networked Programmable Logic Controllers (PLCs) can be targets for cyberattacks, so it’s essential to protect them to maintain the safety of critical infrastructure.

PLC programming is a multidisciplinary skill that integrates software development principles with a comprehensive understanding of industrial processes, electrical systems, and essential safety considerations. This field requires ongoing learning and a practical, hands-on approach.

There are many different PLC manufacturers with their own hardware and software. All programmable logic controllers share similar basic features. To learn how to approach learning about basic PLCs, click here. Click here to learn more about how PLC Simulators can be used to help your programming skills.

Watch on YouTube: Exposing the Secrets of PLC Programming Myths!

PLC Beginner’s Guide to PLC Programming
There are many different PLC manufacturers with other hardware and software. All of the programmable logic controllers have similar basic features. Here is how I would approach learning about basic PLCs.
Once you are familiar with the basics of the PLC, you will then learn specifics for the controller you will be programming.
This is the easiest way to learn about PLC programming.

Here are the controllers that we have covered or are covering at ACC Automation:
LS Electric XGB PLC Series
BRX Do-More Series (Do-More Designer Software + Simulator)
Productivity Series P1000 / P2000
Click PLC Series
Omron CP1H Series
Horner XL4 PLC Series
Arduino Opta PLC

EasyPLC Software Suite is a complete PLC, HMI, and Machine Simulator Software package. See below to receive 10% off this software. This PLC learning package includes the following:
Easy PLC – PLC Simulation will allow programming in Ladder, Grafcet, Logic Blocks, or Script.
HMI System – Easily create a visual human-machine interface (HMI)
Machine Simulator – A virtual 3D world with real-time graphics and physical properties. PLC programs can be tested using the EasyPLC or through other interfaces. (Modbus RTU, TCP, etc.)
Machine Simulator Lite – Designed to run on Android Devices.
Machine Simulator VR – Virtual Reality comes to life so you can test, train, or practice your PLC programming.
Purchase your copy of this learning package for less than $95 USD for a single computer install or less than $110 USD to allow different computers.
Receive 10% off the investment by typing in ACC in the comment section when you order.
Learn PLC programming the easy way. Invest in yourself today.

Examples of PLC program development using the five steps.
Click PLC – Easy Transfer Line Programming – Video
Productivity PLC Simulator – Chain Conveyor MS – Video
Five Steps to PLC Program Development – Die Stamping
PLC Programming Example – Process Mixer
PLC Programming Example – Shift Register (Conveyor Reject)
PLC Programming Example – Paint Spraying
PLC Programming Example – Delay Starting of 7 Motors
PLC Programming Example – Pick and Place
PLC Programming Example – Sorting Station (Shift Register)
PLC Programming Example – Palletizer

If you have any questions or need further information, please contact me.
Thank you,
Garry

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