What is PLC (Programmable Logic Controller) System? How PLCs Work?

What is PLC System? Applications and Benefits

PLC systems are completely used in factories and production areas. The PLC statement consists of the initials of the Programmable Logic Controller. Unlike the computers we use in normal home conditions, there are only a few devices. Unnecessary devices such as CD-ROM are not available on PLC systems. Instead, there are many more mechanical and engineering inputs. Programmable Logic Controller (PLC) that controls many machines and systems through analog-digital input/output connections and for this purpose, digital operations, timing, counter, data processing, comparison, sequencing, 8-16 bit data transfer It is an integrated system consisting of input/output, memory, CPU and programmer sections that provide programming support with the help of input information and assign them to output units.

The first commercial PLC was developed by MODICON company in 1969. PLCs were first developed in the 1970s. In those years, this device, which was developed to be used instead of relay control circuits, was named PLC because only basic logic operations could be performed. After the successful application of the first PLC in the industry, companies such as Allen-Bradley, General Electric, GEC, Siemens and Westinghouse produced high-performance PLCs at medium cost, and later, companies such as Mitsibishi, Omron and Toshiba developed high-performance PLCs at low cost. Later, these devices began to be widely used in industrial automation circuits. They are mainly used in the machine industry instead of large relay panels. In 1978, NEMA (National Electrical Manufacturers Association) established standard PLCs.

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PLC; It is a microprocessor system that processes the information received from the sensors according to the program provided and transfers it to the working staff. Examples of sensors are an inductive sensor that detects any metal, a capacitive sensor that senses an object with static electricity, an optical sensor that detects light, buttons, and switches that are applied to give appropriate voltage to the PLC input. For the working staff, the motors that apply motion energy using the voltage taken from the PLC output, the cylinders used to push and pull an object, the light-emitting lamps are suitable examples.

The devices within the PLC System are as follows;

  • CPU (Central Processing Unit)
  • RAM, ROM (Memory Unit – Memory)
  • IN (Input Unit)
  • OUT (Output Unit)

Scanning can be done very quickly so that the human brain and the computers we use in homes cannot detect. Hundreds of gigabytes of information from the IN partition can be sent to production centers in just a few seconds. This is a much higher cost product.

It can control many processes in the factory or production facility. Thanks to PLC systems, there are no relays with complex systems that reach dozens of lives in our lives. Since PLC systems can control all these from one hand, they are much cheaper and faster. Therefore, large companies and facilities generally prefer PLC systems at production sites.

PLC systems can be seen as a sine qua non of a factory. While many companies produce PLC systems, they design these products with different features. An operator who needs a PLC system must know the specifications of the production company before purchasing this product. While a large PLC system is not needed for a low-data enterprise, a PLC system capable of controlling small data for a company that needs large data will be insufficient.

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Here are the criteria to be considered when purchasing PLC systems;

  • Cost
  • Entry and Exit Points
  • Data Memory and Programming Capacity (By Enterprise Size)
  • Command Processing Speed
  • Time – Real-Time
  • Counter Count and Timer
  • Operating Capability (Cutting)
  • Communication Opportunities
  • Program Backup Opportunity
  • Password Protection (Security Measure against Program Stealing)
  • Technical Support of Purchased Firm

Taking these criteria into account, if a PLC system is purchased, costs can be avoided. Since PLC systems can do the job of many people alone, it provides profit in large enterprises. If you use the human resources of the system that the PLC system and pay your salary costs if you are preventing your profit is absolutely necessary to set up a PLC system for your business. For small size enterprises, PLC systems can be expensive. In general, it is not reasonable for small enterprises to use the PLC system.

Resource: https://www.amci.com/industrial-automation-resources/plc-automation-tutorials/what-plc/

One thought on “What is PLC (Programmable Logic Controller) System? How PLCs Work?

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    29 June 2020 at 00:07
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    Like!! I blog quite often and I genuinely thank you for your information. The article has truly peaked my interest.

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