PLC Programming for Beginners – Types, Features, Benefits, & More

Did you know the market size of PLC is estimated to grow by 4% from 2023 to 2027? PLC, or Programmable Logic Controller, is a specialized computer program commonly used for manufacturing processes and industrial automation. It helps control and monitor various processes in manufacturing plants, machines, and industrial systems. In this blog, we will learn how PLC programming is suited for beginners, and discuss the benefits and risks that come along with it. 

What is a Programmable Logic Controller (PLC)?

A programmable logic controller is an industrial computer without a keyboard that has a high degree of reliability and can run a program without interruption for 24 hours. It is used to control and monitor industrial equipment based on custom programming.

 PLCs have now evolved to deal with the complexities of manufacturing and require a PLC programmer to create and optimize a program according to the unique requirements of a project. Today, PLCs include many features, such as sensor monitoring, protocols to make server-based connections, and ethernet connectivity for data collection.

What is PLC Programming? 

PLC programming is a specialized computer program used for industrial automation and manufacturing processes. It is an essential part of large-scale industries as it helps make work easier and more efficient to handle. It is specially designed to control and monitor the processes and machinery in real time.

The main purpose of PLC is to optimize industrial processes by providing an optimal way of conducting most operations. PLC architecture system comprises three fundamental components, CPU, input/output section, and programming. 

The CPU of the PLC is responsible for executing the operating system and the user program. The operating system organizes functions, sequences, and operations of the CPU. It is tasked with handling hot restart and warm restart, executing user programs, detecting interruptions, managing memory, establishing communication with programming devices, etc. 

The user program is a set of functions that process an automated task. It is created by the user and is downloaded by the CPU of the PLC. It initiates conditions for starting a specific task, reading and evaluating binary and analog input signals, specifying output signals to analog and binary output signals, etc.

PLC Programming for Beginners

If you are a fresher or beginner who has recently started learning this programming language, there are a few important things that you should know before you get started.

• To begin, PLCs use a programming language known as ladder logic. It is a graphical programming language and implies if you’ve worked with GPU before, you’ll be able to take up ladder logic fast.
• Next, a variety of PLC programming software packages are available. You can use those software packages to generate and simulate PLC programs. 
• You can also download your programs to a PLC, which is a beneficial addition for beginners
• After you’ve decided on a PLC programming software package, you can begin learning the fundamentals of ladder logic. 

A few essential tips that every beginner should abide by:

• Start Simple

Begin with a simple program and gradually increase its complexity as you learn more about ladder logic. Do not attempt to develop a complicated program right from the beginning. 

• Use Resources

Make use of available resources on the internet. There are several excellent online tools available to assist you in learning PLC programming. You can always rely on books, tutorials, and even seminars to clear your concepts.

• PLC Simulator

A PLC simulator is a software that allows you to design and test PLC programs. Purchase it as it is an excellent approach to learning ladder logic and testing your PLC programs before transferring them to a real PLC.

• Experience

Getting hands-on experience is a good way to learn PLC. Get on the hunt to find a job or an internship that allows you to work with PLCs. This will help you learn from expert PLC programmers and gain real-world experience.

 How to Start With PLC Programming?

There are three levels of learning PLC programming where you begin at the easy level and then proceed to the advanced as you gain more knowledge and experience. The following are the steps to get started with PLC programming:

• Learn any of the five programming types in PLC. Ladder logic is the most preferred one because it is easy to learn and debug. 
• Focus on learning three important instructions of the ladder logic: examine if closed (XIC), examine if opened (XIO), and output energizes (OTE).
• Now, implement logic routines that use these instructions.
• Analyze their impact on the booleans they are tied to and experiment with different rung configurations in your program. 
• Try to build different structures, keeping in mind the workings of real-life systems. 

When you move from beginner level to advanced, learn additional instructions, such as TON, ADD, TOF, MUL, etc. There will be new data types, add-on instructions, fault-tolerant programming, user-defined data tags, and more. 

Careers in PLC Programming

With heavy reliance on PLCs in manufacturing facilities around the world, there has been an increase in potential career opportunities in this field. Some of the job roles for someone with a PLC programming skillset are:

• Line Operators: The line operators are familiar with the process in manufacturing but do not know how to work the tools. Therefore, their task is to see the smooth functioning of the system and call upon the mechanic or electrician when the need arises. This job is considered to be easier to enter into because there are fewer requirements. It is possible to get started as an operator with a high school education. Their average salary is $14.34 per hour. 
• Mechanics: Because they work in maintenance, they must know the mechanical aspect of the production. Knowledge of PLC programming is essential in their case. Their average salary is $17.67 per hour and $6,750 per year. 
• Electricians: Their skills vary from someone trained to working with electrical systems and other PLC programming, network infrastructure, or field devices. Formal training is required to become an electrician because only licensed electricians are hired in manufacturing units. They get a higher salary than mechanics, the average pay is around $23.56 per hour. 
• Control System Engineers: They have the knowledge and expertise in the entire manufacturing process, troubleshooting the systems, and modifying them for better efficiency. If you are considering the role of an engineer, ensure that you are well-versed in PLC programming. Their average annual salary is $60,711. 

Devices in PLC

PLC or programming devices work with the PLC program in creating, modifying, or troubleshooting. Two of the most common PLC devices are:

• Handheld Programming Device: It is a compact and easy-to-use device connected to the PLC with a cable and contains a set of keys that permit one to enter or edit the code into the PLC. Programmed instructions are visible through a small screen or display. 
• Personal Computers (PC): Along with software provided by the manufacturer, these are used to program PLC. The program can be run using the PC in both offline as well as online modes. The PC contains the program code corresponding to the control application transferred to the PLC CPU through a programming cable. 

Some popular PLC brands are Allen Bradley, SIMATIC, and AC500.

Types of PLC Programming

There are five main types of PLCs as mentioned below:

• Ladder Logic: It is a graphical language that represents logic gates and electrical components using symbols. It is simple to understand and apply and is ideal for situations requiring sequential control.

The ladder logic comprises two parallel bars connected by a series of rungs. The rungs have contacts that represent the input and coils that represent the output. It is based on relay logic’s circuit diagram and is similar in appearance to a ladder. Below is a brief illustration of how a ladder logic diagram looks.

• Function Block Diagram: It is a graphical language that represents complicated processes using function blocks. Since function blocks may be reused in several applications, FBD is an excellent solution for big and complicated projects.

It consists of several types of blocks that have inputs and outputs. For devices that are connected to a PLC, we can connect them to an input and variables to the output. Since these blocks are connected, the output of one block can be fed into the input of another block. The functions of a system are defined by these blocks. Below is a brief illustration of how a functional block diagram looks. 

• Sequential Function Chart: It is a graphical language that represents the sequence of events in a PLC program using flowcharts. It is an excellent solution for applications requiring sophisticated timing and sequencing.

Its architecture resembles a flowchart that comprises steps and transitions that control the operational flow of the program. Here, steps represent the actions to be performed and the transitions represent the logical conditions necessary to be met before the process can move to the next step. 

It allows the division of complicated processes into various manageable parts and is ideal for linked processes, batch production, and complex multi-state production. 

Below is a brief illustration of how a SFC diagram looks.

• Structured Text: It is a textual programming language that represents logic processes with keywords and sentences. 

In the structured text, we use statements or lines of code to perform functions. It works similarly to the programming languages C++, C, Python, or Java. It is readable and executes quickly but is difficult to troubleshoot as states of variables are not easily detectable. 

Structured text is useful for manipulating or searching data, barcode parsing, working on machine code, looping, etc. 

• Instruction List: It is a textual programming language that employs symbols to describe individual instructions.

Similar to assemble language, an instruction list comprises a simple series of steps. It follows a tight structure where each line gives specific instructions, along with conditions and outcomes of the execution to create a process flow. It requires the user to create a variable explicitly. A benefit of the instruction list is that it maintains a level of clarity on how the data will be processed. 

Note that the instruction list is depreciated in the ICE or International Electrotechnical Commission’s standard, making it a less popular method for programming PLCs now.

Below is a brief illustration of how an instruction list diagram looks.

To learn more about the types of PLC, you can opt for this comprehensive PLC programming course.

Also Read: Advantages Of PLC

Benefits of PLCs

The following are some of the benefits that PLCs have to offer.

• Flexibility: They are ideal for dynamic industrial applications because they allow for fast alterations and upgrades without the need for major rewiring or hardware changes. 

• Reliability: PLCs have a high level of dependability and can function continuously for long periods without fail as they are designed for industrial use.

• Scalability: They can be scaled easily to meet various system sizes and complexity to enhance their capabilities without requiring major reconfiguration.

• Affordability: They minimize the need for complicated and expensive wiring, save installation time, and allow for more effective resource utilization. 

Risks of PLCs

The following are some of the risks of PLCs:

• The programming in PLC can become complex sometimes since not all functions are easy to perform.
• The processing power is limited.
• It lacks standardization which makes it difficult to switch between brands.
• The connectivity it offers is not always smooth and can be troublesome.
• The system is more open to vulnerabilities and cyber risks.

Top Industries that Use PLC Programming

Various industries use PLC to enhance their automation process and increase the efficiency of operations. The following are the top applications of PLC programming.

• Automobile Industry
• Food Processing Industry
• Oil and Gas industry
• Paper Industry
• Glass Industry
• Mining Industry
• Cement Industry

Future Scope of PLC Programming

Several industrial automation applications are using PLCs today. Various features such as scalability, memory, built-in wireless features, programming flexibility, etc. have widely increased the scope of PLC programming. USB technology has significantly helped the PLCs for online programs and efficient monitoring of control systems. 

With the integration of micro, small, and mini USB connectors, PLC programming will continue to evolve. In the future, it is anticipated that it will adapt to more enhancements in software, hardware, and communication technology.

Conclusion

This blog gave you insights into PLC programming for beginners. PLC is a specialized computer program designed for industrial automation. You must learn about the basics of this programming before you start working with it. As more businesses implement automation technology, the demand for PLC programmers is projected to rise in the future years. If you’re looking for a job in this field, this resource on PLC interview questions can help you prepare well for your interview. 

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