Programmable logic controller Training An efficient system

In this article you will know everything you need to know about a programmable logic controller , from its beginnings to the present. Go ahead and discover the advantages of this incredible computer! programmable logic controller training

Programmable Logic Controller Training

A programmable logic controller , sometimes simply called a PLC, is nothing more than a computer by which various electromechanical processes are automated. It includes a programmable memory where the instructions required for the implementation of specific functions on various types of machines and processes are stored. programmable logic controller training

programmable logic controller training
programmable logic controller training

Currently, programmable logic controllers are used in various types of industries, in addition to being present in other sectors such as: scientific, military, education, medicine, technology, research, banking, security, and others. This is mainly due to the evolution of hardware and software.

Among the tasks that can be executed by means of a programmable logic controller , we can mention the checking of the centralized programming of each of the parts that make up the processes, the operation of both the machines and the facilities, the automation of domestic processes , the installation of security controls, and many others.

To learn more about this fascinating topic, I invite you to read the article on automated processes . In it you will find relevant information about its operation, the requirements for its implementation, its advantages and disadvantages.

History programmable logic controller training

The origin of programmable logic controllers is due to the beginning of the era of industrialization. In this way, in 1960 the first control systems emerged that replaced the use of relays and contactors, which made it possible to reduce the costs of installation and maintenance of production lines.

Eight years later the first programmable controllers appear, made up of a control system through a computer. These programmable robots turned out to be inexpensive, robust, flexible, and easy to modify. In addition to being able to work under adverse conditions, its useful life was greater than that of the models that preceded it.

programmable logic controller training
programmable logic controller training

Later, in 1970, digital logic systems emerged, which were built with microprocessors or integrated circuits, being capable of developing specific tasks, and not for general use. Additionally, they could exchange information with each other without being near the processors. programmable logic controller training

Almost in the late 1970s and early 1980s, the first models of programmable logic controllers were developed, which allowed both analog and numerical remote inputs and outputs. Thanks to the increase of its memory, it was possible the incorporation of functions of control of positioning and the increase of the communications with computers and peripheral devices.

Similarly, programming languages ​​with greater power and functionality appeared.

Later, in the mid-1980s, the standardization of communications began with the appearance of the MAP protocol. The dimensions of the programmable logic controllers were made smaller and programming began using personal computers.

For its part, the decade of the 90s was characterized by a gradual reduction of the new protocols, as well as by the modernization of the physical layers of the existing protocols at the time. The development of multiprocessor modules led to the standardization of the programming of programmable logic controllers, at the same time that communication between different brands of controllers and computers was possible.

Later, starting in the year 2000, multiple programming opportunities were generated from multiprocessor modules. In addition, the availability of task control, monitoring and supervision applications increased, which led to a greater presence of fully automated factories. programmable logic controller training

The programmable logic controllers increased their responsiveness and accuracy, in a minimum footprint and at a reasonable cost. Additionally, they turned out to be easy to install and, contrary to popular belief, require less maintenance.

features programmable logic controller training

A programmable logic controller has the following characteristics that differentiate it from traditional computers:

  • It does not have a keyboard, screen, mouse, or hard drive, but it does have processors, memory, and communication ports within its hardware.
  • It contains software that acts as the operating system, called Firmware, and specific programming for the application you use.
  • It supports wide temperature ranges, without affecting its proper operation.
  • It is immune to electrical noise and resistant to vibrations and impact.
  • The control programs are stored in non-volatile memories or, failing that, in backup batteries.
  • The exit results are, necessarily, a consequence of the entry conditions in a determined and limited time.

Advantage programmable logic controller training

Due to its wide field of application, a programmable logic controller has many advantages. The main ones include the following:

  • Its design allows the understanding and processing of multiple input and output signals, coming from sensors installed in the machines or processes they control.
  • It allows the human operator to carry out work in an agile and practical way, including the monitoring and diagnosis of conditions.
  • Thanks to its short reaction time to the variable conditions it controls, it is possible to carry out operations in real time.
  • They are flexible programming teams, which allows them to easily adapt to new functions.
  • Due to its easy adaptation to changes, the additional costs inherent in the development of new projects are minimized.
  • Immediate communication with other types of controllers is possible.
  • Allows networking with multiple computers and various controllers.
  • Their construction is stable, which makes them resistant to extreme conditions, such as: humidity, various temperatures, noise and vibrations in general.
  • Its programming is simple, as it is compatible with truly understandable programming languages.
  • It reduces the risk of occupational accidents, related both to human elements and to the surrounding environment.
  • It requires little space for installation.

Disadvantages programmable logic controller training

Fortunately, the drawbacks of implementing a programmable logic controller are few. They are based on the need to have:

  • Qualified personnel for its operation and control of tasks.
  • Frequent maintenance.
  • Constant technical training.

External structure programmable logic controller training

A programmable logic controller is made up of the following external elements:

  • Digital inputs and outputs: They allow communication between the programmable logic controller and the signals and actuators of a specific application. Switches and, in some cases, sensors are connected to the inputs. While the outputs are located lamps and different types of coils.
  • Power source: It is responsible for feeding the programmable logic controller , supplying it with the voltages and currents necessary for its operation. It is also in charge of feeding the auxiliary circuits.
  • Housing: Refers to the faceplate of the programmable logic controller.
  • Operator control: It is physically located in the housing of the programmable logic controller . Its function is to allow or stop the execution of the program, through the action of the human operator. programmable logic controller training
  • Programming interface: Also called communication interface, it is responsible for the transfer of the program, from the handheld programmer to the controller or personal computer that contains the appropriate software.
  • Expansion modules: Through them it is possible to increase the number of inputs and outputs of the programmable logic controller , according to the requirements of the application.

Internal structure

The internal structure of a programmable logic controller is made up of the following electronic elements:

  • Central processing unit: Commonly called CPU, it is responsible for executing most of the system processes derived from the programs, both configuration and user. It contains a microprocessor, capable of performing the logical and arithmetic operations required for data processing.
  • Memory: It is responsible for storing system information, in the form of numerical data arranged in binary code. Includes read-only memory and read-write memory.
  • Ports: Allow the programmable logic controller to communicate with other devices, including digital input and output devices. programmable logic controller training
  • Modules: Refers to more sophisticated and specialized ports that require very little involvement from the central processing unit. These include counters, timers, modular pulse width generators, analog-digital converters, digital-analog converters, serial communication modules, and field buses.

General operation programmable logic controller training

A programmable logic controller works cyclically, correspondingly complying with the instructions indicated in the user program stored in its memory. In this way, its operating cycle consists of the following stages: programmable logic controller training

  • It performs its own routines inherent to the maintenance of the system, such as memory control and diagnostics. This part of the cycle is not perceptible to the user.
  • It loads the values ​​of the digital inputs, converting them into binary or digital signals, which are saved in the memory data and sent to the central processing unit.
  • Execute the user program, once each instruction has been sequentially loaded into memory. During this phase, new outputs are generated. programmable logic controller training
  • It loads the output signals, be they binary, digital or analog, and sends them to the digital memory output. These signals become the appropriate ones for the actuators.

In this regard, it is important to note that at the end of each of the stages, the programmable logic controller starts a new cycle. The time it takes to carry out this operating cycle determines its speed and establishes what application it is really used for.

Setting programmable logic controller training

The industrial communication system used by programmable logic controllers is based on the Master – Slave model, in which the device called Master governs the communication cycles, being able to modify the structure, algorithms, assignments and settings of the other devices. , called Slaves.

In this way, the Slave is only allowed to respond to the Master’s requirements when it corresponds, being also responsible for the execution of the data processing, from where it obtains the resources to efficiently comply with the transaction process.


There is a wide range of programmable logic controllers, but the main ones include the following:

  • Compact PLC: All its components are integrated within the same package. It has limited capacity for digital input and output modules, as well as for communication channels.
  • Modular PLC: It has greater power and functionality than the compact PLC, allowing the use of a greater number of inputs / outputs. In addition, it supports more complex programs and has greater memory capacity to store data.
  • Rack-mount PLC: It has similar characteristics to the modular PLC, but it differs from them because the rack contains slots for the modules and an integrated bus system, capable of establishing communication between the different modules.

Other types of programmable logic controllers are: PLC with operator panel and programmable logic controller, PLC with industrial computer, slot-type PLC, and software-type PLC.

Signs programmable logic controller training

A programmable logic controller receives and transfers electrical, binary, digital, and analog signals.

  • Binary signals: It refers to the one-bit signal that contains only two possible values, 0 and 1. Its activation opens the contact coded with the logical value 1.
  • Digital signals: It consists of a sequence of binary signals, which are considered as a unit.
  • Analog signals: These are continuous values, that is, they contain an infinite number of values.


Before deciding the type of programmable logic controller that we want for a certain application, it is important to take into account the following aspects:

  • Number of digital inputs and outputs.
  • Number of timers and counters.
  • Available memory size.
  • Volatility.
  • Communication protocols.
  • Information processing speed.


  • A programmable logic controller is a computer used to automate different types of machines and processes.
  • Its main function is to improve the conditions of productivity, efficiency, precision and reliability of the systems in general.
  • The field of application of programmable logic controllers is not limited to the industrial sector, being present in almost any area of ​​our life, including the domestic one.
  • The main types of programmable logic controllers that exist are compact, modular, and rack-mountable.
  • The most used configuration, referring to the established communication cycle, is that of Master – Slave.
  • The operating cycle is cyclical and consists of four stages.

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