The History of the PLC

In 1968, Dick Morley created the concept of the PLC. Its original name was “Standard Machine Controller”, and in 1969 the MODICON company launched the first commercial PLC and first PLC network.

As a result of its earlier success, throughout the years up to the present, multiple companies such as Allen Bradley and Siemens have manufactured more high-tech PLCs.

  • Allen Bradley: 1174 PLC, PLC 5, SLC-500, MicroLogix 1000, ControlLogix
  • Siemens: Simantic S5, Simantic S7

What is a PLC?

PLC stands for Programmable Logic Controller; we use this computer across many industries but primarily in industrial automation. It is a solution for manufacturing companies and processes.

PLCs work to automate and control a machinery’s process, functions, or even an entire production line. 

How does it work?

Different units compose a PLC; Those units are a CPU module, a power supply, a programming device, and input/output modules (analog or digital). 

  • The power supply provides power to all modules of a PLC. It transmits AC power which is converted to DC power. 
  • The programming device provides the software needed for the control logic system. Engineers can customize it to meet the desired process/functions.
  • The CPU is the brain of the operation. Not only does it store all the information, but it also computes data and executes tasks.
  • The input module collects data and feeds it to the PLC system; Which produces readable information redacted through the output module.

Programming Languages:

The PLC program is usually written on a computer and downloaded to the controller. The most used programming language is Ladder Logic, also known as Ladder Diagram (LD).

However, the International Electrotechnical Commission (IEC) identifies the 5 most common standard programming languages for process and programming:

  1. Ladder Diagram (LD)
  2. Function Block Diagram (FBD)
  3. Sequential Function Chart (SFC)
  4. Instruction List (IL)
  5. Structured Text (ST)

Why do businesses use PLCs?

The PLC has been an essential piece in the manufacturing industry since it enables manufacturers to increase proficiency, efficiency, and market value. It also decreases human error, and in some processes reduces cycle time and scheduling. The PLC provides many other benefits like monitoring conditions of the equipment and detecting abnormalities in the system in order to prevent running an unsafe process.

One of the primary reasons that businesses choose PLCs is the flexibility of the system to accomplish a multitude of tasks. PLCs are not only simple to program but also hold a vast amount of data. In addition, businesses also opt for PLCs since they work well with other systems, such as HMIs and motion control devices.

The Growing Market for the PLC

Furthermore, despite the COVID-19 Pandemic in 2020, the global market for PLCs was valued at $12.3 billion. The arrival of Industry 4.0 and digital transformations to come will not leave PLCs behind. This can be seen in PLCs projected 4.6% global growth rate between 2020-2027.

There are a plethora of reasons why PLCs are crucial and valuable in the manufacturing industry. In a nutshell, these reasons include design, low cost, and how it easily handles complex integrations.

ICA recognizes the value of this amazing tool, which is why our engineers have mastered their PLC programming skills, and keep mastering them with every update there is. We work with top brands and keep the latest PLCs on the market in stock! If you can’t find a product you need on our website or you are looking for more information on PLCs, please do not hesitate to contact us.

By Grace Ramirez.


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