Introduction to automation ,plc, programing language

Sanjivani Rural Education Society’s
Sanjivani College of Engineering, Kopargaon-423 603
(An Autonomous Institute, Affiliated to Savitribai Phule Pune University, Pune)
NACC ‘A’ Grade Accredited, ISO 9001:2015 Certified
Department of Electrical Engineering
B. B. Kadam
Assistant Professor
E-mail : kadambhushanelect@sanjivani.org,in
Contact No: 7020447673
Subject- PLC & SCADA
[Electrive II (317 C)]
Unit 1 - Introduction to Automation and PLC
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Contents
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1. Need & Role of Automation,
2. Types of Industrial Automation System
3. Definition & History of PLC,
4. Basic structure & Components of PLC
5. Principle of Operation, Selection of PLC, PLC I/O Modules, Memory,
6. PLC advantages & Disadvantages,
7. What is Logic? Overview of Logic functions
8. Number systems & Codes
9. Hardwired Logic vs Programmed logic.
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1. Need & Role of Automation,
DEPARTMENT OF ELECTRICAL ENGINEERING, Sanjivani COE, Kopargaon 3
❖ Increased Reliability
❖ More Flexibility
❖ Lower Cost
❖ Communication Capability
❖ Faster Response Time
❖ Easier Troubleshooting
❖ Easy to Test Field Devices
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2. Types Of Industrial Automation System
❖ Fixed Automation System
❖ Programmable Automation System
❖ Flexible Automation System
❖ Integrated Automation System
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3. Definition & History of PLC,
❖ A modern controller device used extensively for sequence control today in transfer
lines, robotics, process control, and many other automated systems is the
Programmable Logic Controller (PLC). In essence, a PLC is a special purpose industrial
microprocessor based real time computing system, which performs the following
functions in the context of industrial operations
5

Department of Electrical Engineering 6
An original Modicon PLC. Image used courtesy of Schneider Electric

4. Basic Structure & Components of PLC
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5. Principle of Operation, Selection of PLC, PLC I/O Modules, Memory
Operational Sequence
❖ Scan Cycle:-checks on the hardware and software for faults, also called a self-test
1. Input Scan: A simple way of looking at this is the PLC takes a snapshot of the inputs and solves the logic. The PLC
looks at each input card to determine if it is ON or OFF and saves this information in a data table for use in the next
step. This makes the process faster and avoids cases where an input changes from the start to the end of the program.
2. Execute Program (or Logic Execution): The PLC executes a program one instruction at a time using only the
memory copy of the inputs to the ladder logic program. For example, the program has the first input as ON. Since the
PLC knows which inputs are ON/OFF from the previous step, it will be able to decide whether the first output should be
turned ON.
3. Output Scan: When the ladder scan completes, the outputs are updated using the temporary values in memory. The PLC
updates the status of the outputs based on which inputs were ON during the first step and the results of executing a
program during the second step. The PLC now restarts the process by starting a self-check for faults.
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5. Selection of PLC, PLC I/O Modules, Memory
❖ Power Supply
❖ Number of Inputs and Outputs
❖ Communication Protocol
❖ Environment Specifications
❖ Motion Requirement / Speed of CPU
❖ Application Requirements of PLC
❖ Operator Interface
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6. PLC advantages & Disadvantages,
❖ Advantages
❖ Reliability
❖ Flexibility
❖ Ease of use
❖ Cost-effectiveness
❖ Safety
❖ Disadvantages
❖ Complexity:
❖ Limited processing power: PLCs are not as powerful as some other types of systems like DCS, and they may not be
able to handle complex tasks or large amounts of data.
❖ Limited expandability:
❖ Dependence on programming:
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,
Ladder logic is a fast and simple way of creating logic expressions for a PLC in order to automate repetitive machine tasks
and sequences. It is used in a multitude of industrial automation applications. Some industrial automation application
examples where PLC ladder logic is used include….
● Material Handling Conveyor System.
● Pallet Packing and Strapping.
● Ball Mill Lubrication System.
● Logistics Package Conveying and Sorting.
● Cement Batching.
● Beverage Bottling and Labeling.
● Hopper and Tank Level Control.
● Air and Liquid Flow and Pressure Control.
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Functional Block Diagram

,
https://learn.automationcommunity.com/courses/siemens-plc-tia-portal-training-course
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8. Number systems & Codes
,
❖ Decimal number system (Base- 10
❖ Binary number system (Base- 2)
❖ Octal number system (Base-8)
❖ Hexadecimal number system (Base- 16)
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,
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STATE-I (NO) STATE-II (NC)
RELAY OPERATION

,
❖ Relay Logic Vs Ladder Logic - Ladder Logic World
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Hardwired Logic vs Programmed logic.
Hardwired Logic Programmed logic.

HARDWIRE LOGIC PROGRAMMABLE LOGIC
Difficult to develop complex logical expressions with
relay logic.
Easier to develop complex logical expressions with
ladder logic software.
The life of relay based system is less as compared to
PLC
Increased reliability with PLC life easily reaching +10
years,
Expansion of the system is difficult as well as costly Easier and cheaper to modify or expand the control
system at a later date.
More time is required for design, installation and
component
Reduced design, installation and component costs
Relays required continuous maintenance. Virtually maintenance free compared to relays
Superior monitoring and reporting functionality are not
available with hardwire logic
Superior monitoring and reporting functionality making
process troubleshooting and optimization easier.
Auxiliary devices are required such as timer or counters No need to Add auxiliary timer or counters

DEPARTMENT OF Electrical ENGINEERING, Sanjivani COE, Kopargaon 21
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Introduction to automation ,plc, programing language

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