What is automation ? | History of Automation

What is automation ?

Benefit of automation is that it saves labor; however, it is also used to save energy and materials and to improve quality, accuracy and precision.

Automation is basically the delegation of human control function to technical equipment for

  1. Increasing productivity

  2. Increasing robustness (consistency)

  3. Reducing direct human labor costs and expenses.

  4. Increasing quality

History of automation

Manual Control

Pneumatic Control

Hard wired logic Control

Electronic Control using Logic Gates

Programmable Logic Controller

1. Manual Control

All the actions related to process control are taken by the operators manually.


Likely human errors and consequently its effect on quality of final product.
The production, safety, energy consumption and usage of raw material are all subject to the correctness and accuracy of human action.

2. Pneumatic Control

Industrial automation, with its machine and process control, had its origin in the 1920s with the advent of "Pneumatic Controllers“.

Actions were controlled by a simple manipulation of pneumatic valves, which in turn were controlled by relays and switches.


Bulky and Complex System

Involves lot of rework to implement control logic

Longer project time

3. Hard wired logic Control

The contactor and relays together with hardware timers and counters were used in achieving the desired level of automation


Bulky panels

Complex wiring

Longer project time
Difficult maintenance and troubleshooting

4. Electronic Control using Logic Gates

In 1960s with the advent of electronics, the logic gates started replacing the relays and
auxiliary contactors in the control circuits.

The hardware timers & counters were replaced by electronic timers.


Reduced space requirements
Energy saving
Less maintenance & greater reliability


Changes in control logic not possible
More project time

5. Programmable Logic Controller

In 1970s with the coming of microprocessors and associated peripheral chips, the whole process of control and automation underwent a radical change.

Instead of achieving the desired control or automation through physical wiring of control devices, in PLC it is achieved through a program or say software.

The programmable controllers have in recent years experienced an unprecedented growth as universal element in Industrial Automation.

It can be effectively used in applications ranging from simple control like replacing small number of relays to complex automation problems.

Advantages of PLCs

Reduced space

Energy saving

Ease of maintenance


Greater life & reliability

Tremendous flexibility

Shorter project time

Easier storage, archiving and documentation

Industrial automation main components

Field instruments
Control hardware
Control software

Automation : Typical installation…


Automation : Typical installation…


Sensors or Transducers (Field Instruments)

Sensors are used to sense the changes in physical parameter like Temperature, Level, Flow, Humidity, Pressure and many others…

Transducers are used to convert not electrical quantity to electrical signals

Hence it concludes, sensors and transducers are placed in field to sense the physical parameters and send the electrical signal of respective changes to control rooms.

These signal are either digital or analog signals for example, Ohm(RTD), mv(Thermocouple), standard 4-20mA signal, etc.

Widely used field instruments in industries

Flow transmitters (Orifice, Ventury, Electromagnetic flow meter etc)

Pressure transmitters (Bourdon gauge, Bellows, Diaphragm, etc)

Temperature transmitters (Thermocouple, RTD, Thermister, etc)

Level Transmitter (Ultrasonic transmitter, Radar type, capacitive type)

pH transmitter

Conductivity Meter…etc

Famous manufacturing companies (Field instruments)

Fisher Rosemount
Forbes Marshall
Honeywell ABB

Control hardware

Standalone PID Controllers
Programmable logic controllers
Distributed control system

1. Standalone PID Controllers


These are the small controlling hardware which fulfill the requirement of closed loop.

This can be installed in field or in control room

Every companies have variations in programming patterns to setup PID configuration

Typical installation of standalone PID controller

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Master slave communication with RS485

Famous manufacturing companies in PID controllers

Forbes Marshall

2. Programmable logic controllers

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A programmable logic controller (PLC), or programmable controller is an industrial digital computer which has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high reliability control and ease of programming and process fault diagnosis.

What is inside PLC ?

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Architecture of PLC

A programmable logic controller (PLC), is a like a microcontroller which is used for doing so many applications.

It basically consist of

  1. CPU with processor and program memory

  2. Power supply

  3. Input module

  4. Output module

  5. Control bus

1. Parts of Delta PLC


2. Parts of Allen Bradley PLC


3. Parts of Siemens PLC


4. Parts of Zelio Schneider electric PLC


Distribution of I/O’s through controller


Distributed control system (DCS)

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General architecture of DCS

System cabinets and Marshalling cabinets of DCS

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System and Marshalling cabinet arrangement

Various DCS and Hybrid DCS providing companies


  1. Yokogawa (Centum VP)

  2. Honeywell (EPKS)

  3. Emerson (Delta V)

  4. Forbes Marshall

Hybrid DCS

  1. Allen Bradley (Compact logix and control logix)

Various Communication protocol used in DCS or PLC systems and its hierarchy


LAN (Ethernet)

Modbus, CAN, Serial communication

OPC (OLE for Process Control)

Control NET

Foundation Field bus

Profibus (DP,PA)

Device NET

Various languages used in PLC and DCS

Ladder Logic ( LAD/LD)

Function Block Diagram (FBD)

Sequential Function Chart (SFC)

Structured Text (ST)

Instruction List (IL )

Supervisory Control and Data Acquisition software (SCADA)

               SCADA (supervisory control and data acquisition) is a category of software application program for process control, the gathering of data in real time from remote locations in order to control equipment and conditions.

Features of typical SCADA software

Dynamic process graphic

Real-time and Historical trending


Recipe Management


Device connectivity

Script for logic development

Database connectivity

Displays used for monitoring in SCADA systems



Some SCADA software available in market

Intouch (Wonderware factory suit)

Wincc (Siemens)

Simplicity (GE Fanuc)

RS View32 (Allen Bradley)

Flow of project in industry


Core branches/career of Instrumentation and its scope in Industry



Engineering Procurement and construction

Designing of total plant

Automation work includes in EPC companies

Designing of P&ID drawings


Designing of the Automation system

Erection and Commissioning

Maintenance and Troubleshooting of existing system

Author - Tushar Bhaskarwar