Skip to main content

Programmable Logic Controllers (PLC) - The Brain behind Industrial Automation




The Start ....

With the advent of industrial age, machines were used to automate process, which were routine in nature. This greatly allowed the reduction in production cost, benefitting the consumers.

Earlier Relay Logic Devices  based on electromagnetism, were used to control machinery. 

Two circuits, one with an open switch and another with a coil of wire, were placed parallel to each other. When current passes through the coil, it produced a magnetic field. This created a force of attraction, and the switch closes. The circuit gets completed, allowing the flow of current. This in turn drives a motor or an actuator.

Being a cost-effective solution, there were still some downsides. The installation part was highly complex. 

A breakthrough came in 1964, when Dick Morely, an American inventor, designed a general-purpose computer to control industrial applications.

Known as Programmable Logic Controllers, or PLC, it brought about a revolution in industrial automation.

What is PLC 

A specialized computer which can perform logical operations, while withstanding harsh environmental conditions like dust, humidity and temperature.

Based on the relay logic technique, switching was done digitally with electronic circuits and coding. This reduced overall complexity and installation overhead.

Ladder Logic is the coding language used. Also C/C++ in certain cases. 

Components

The internal layout of PLC consist of five main components

1. Processor: Dubbed the brain of the computer, the microprocessor performs logical and analytical computations, based on environmental variables. 

2. Input: The module that receives signals from sensors, or other measuring devices. Can be either analog or digital. This is then passed to the processor.

3. Output: Gets the calculated data from the processor, and converts it to readable signal. This in turn drives a motor, or an actuator.

4. Memory: Split into two divisions, the RAM (Random Access Memory) is used to store temporary data. ROM (Read Only Memory) stores the Operating System and programs, installed by the user.

5. Power Supply:  220V Alternating Current is converted into Direct Current. It is further split into smaller voltages to be fed into different components



The PLC is by definition a Real Time Operating System. The inputs are continuously scanned for any changes, and processor is always on stand by mode. 


More information:

 

Labels:

Comments

Post a Comment

Popular posts from this blog

Man In The Middle Attack - EavesDropping in the Digital World

    This is a term used to describe a cyber attack where a hacker acts as middleman, during data transfer between user and an application. The app can be a financial or an E commerce website, Software as a Service (SaaS) etc. The hacker can intercept data passed via the browser to the website, and collect sensitive information such as account and credit card details, user login etc. To put it into context, it is like a postman who reads all the letters addressed to you, then reseals the same, on delivery. This way no one suspects a foul play.   Interception This is the first phase of the attack. Here the hacker establishes a connection with the target device whether a PC, Laptop or Smart phone. This is done   through various methods   like   Free WiFi  : Here a WiFi hot spot is set up  which is not password protected. When a user logs in to the network, they are in essence connecting to the hacker's system. Now any data transfer occurs via this co...
Post a Comment
Read more

Internet of Things-Connection Redefined

  Imagine driving home after a long day of work. En route the car instructs the residence to automatically turn on the lights, prepare a hot bath, and download the latest Netflix series. While this may seem like a line from a SciFi script, the future is more realistic than ever. Welcome to the world of IoT or Internet of Things. Though not as popular as its famous counterpart, Artificial Intelligence, its penetration into the consumer market is indeed extensive. What is IoT...... It is the term used to describe a   device, or set of devices which are connected to the internet,   and also communicate with each other. They can share data obtained from various sensors to a central hub, analyze it using  AI, and take appropriate actions. For example, a smart thermostat can read the room temperature, analyze the same, and adjust the heating system without any human intervention. Another example would be a smart camera which provides video footage when a movement is detect...
Post a Comment
Read more

Bluetooth - You are Connected

       We are entering the era of Internet of Things (IoT) devices, where each device connects remotely to one another, and the world wide web. This makes them smart in the way of integration to Artificial Intelligence, Machine learning and Data analysis. There are number of network protocols that facilitate this peer to peer communication be it ZigBee, Matter etc. More on that later.    What is Bluetooth  Invented  in 1994 by Ericsson and widely used, Bluetooth allows for short distance communication, within 10 meter radius. The data speed is between 1 Mbps and 3 Mbps. The bandwidth is in the range of 2.4 GHz to 2.485 GHz.   Frequency Hopping Unfold Spectrum This is the underlying tech used in Bluetooth. Data signals by default have low frequency, and high bandwidth. This makes them prone to distortion, affecting long distance transmission. Also the receiving antennas  have to be large in size which is a limitation for mobile phone...
Post a Comment
Read more