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PREPARED BY: SANTOSH.B.MANKANI M.Tech(TPE)
SELECTION GRADE LECTURER (MECHANICAL)
GPT RAICHUR
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 2 of 30
Introduction to Mechatronics
Mechatronics is defined as the interdisciplinary field of engineering and design methodoly. It deals
with the design of products whose function relies on the integration of mechanical, electrical and
electronics components connected by a control scheme. Mechatronics plays an important role in the
design manufacturing and maintenance of a wide range of engineering products and process.
Mechatronics provides solutions that are efficient and reliable systems.
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 3 of 30
MECHATRONICS LAB
PART-A
Design and simulate the following digital circuits using MultiSim/any digital
circuit
1. Basic Logic Gates
2. De Morgan’s Theorem
3. Combination Logic 4. Encoders and Decoders
5. Digital Oscillator
6. Flip-Flops
PART-B
1. Draw the ladder rungs to represent
i. Two switches Normally Open and both have to be closed for the motor to
operate.
ii. Either of the two Normally Open switches to be closed for the coil to be
energized
2. Devise a timing circuit that will switch on for 20s and then switch it off.
3. Device a timing circuit that will switch on 10s and off 20s and so on....
4. Device a circuit that can be used to start a motor and then to start a pump after
delay of 50s. Then the motor is switched off 10s before the pump is switched off when
the pump remains on for 50s.
5. Devise a circuit that can be used with the domestic washing machine to switch on a
pump to pump water for 100s into the machine. Then switch on a heater for 50s to
heat the water. The heater is switched off and another pump is switched on to empty
the water for 100s.
PART-C
Design and simulate the following systems using Automation Studio/Any
equivalent Simulator Software.
1. Design and simulate of fluid power circuits to control (i) Velocity
(ii) Direction of a single and double acting actuators
2. Design and Simulate a ladder diagram for car parking.
(Hint: car is to be detected and enter the parking space to a particular location
if space is available. If there is no space, a lamp should indicate that parking
is full. )
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 4 of 30
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 5 of 30
A B A+B=Q
0 0 0
0 1 1
1 0 1
1 1 1
Exercise No: 1
Aim:
OR GATE
Conduct an experiment to Design and simulate logic circuit of OR gate.
Components:
1. OR gate - 1 No.
2. Logic switch - 2 Nos 3. 3. Logic Display - 1 No.
4. Out Put Display -1No
Software Used:
Electronics work bench software, logic gates simulator
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
i All basic logics gates are designed and simulated using digital circuit simulator.
ii The outputs will be recorded in the truth table
Logic Symbol Boolean Equation
A+B=Q
Logic Circuit Truth Table
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 6 of 30
A B A.B=Q
0 0 0
0 1 0
1 0 0
1 1 1
Exercise No: 2
Aim:
AND GATE
Conduct an experiment to Design and simulate logic circuit of AND gate.
Components:
1. AND gate - 1 No.
2. Logic switch - 2 Nos
3. Logic Display - 1 No.
4. Out Put Display -1 No.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
The AND gate performs logical multiplication, more commonly known as the “AND” function. An
AND gate has two inputs and one output. An AND gate gives an output “1” when both of its inputs
are “1”. For all other combinations of inputs it gives an output “0”.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit of AND gate is designed and simulated. Simulation of the circuit satisfies the truth table.
Logic Symbol Boolean Equation
A.B=Q
Logic Circuit Truth Table
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 7 of 30
A A=Q
0 1
1 0
Exercise No: 3
Aim:
NOT GATE
Conduct an experiment to Design and simulate logic circuit of NOT gate.
Components:
1. NOT gate - 1 No.
2. Logic switch - 1 No.
3. Logic Display - 1 No.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
A NOT gate produces an output that is a complement of the input. It has only one input signal and one
output signal. It gives an output “1” when its input is “0‟ and vice versa. Thus, a NOT gate is also
known as “INVERTER”.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit of NOT gate is designed and simulated.
Logic Symbol Boolean Equation
A=Q
Logic Circuit Truth Table
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 8 of 30
A B A+B=Q
0 0 1
0 1 0
1 0 0
1 1 0
Exercise No: 5
Exercise No: 4
NOR GATE
Aim:
Conduct an experiment to Design and simulate logic circuit of NOR gate.
Components:
1. NOR gate - 1 No.
2. Logic switch - 2 Nos
3. Logic Display - 1 No.
4. Out Put Display - 1 No.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
The term NOR is a contraction of NOT-OR and implies an OR function with an inverted output. A
NOR gate gives an output “1” when both of its inputs are “0”. For all other combinations of input it
gives an output “0”.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit of NOR gate is designed and simulated.
Logic Symbol Boolean Equation
A+B=Q
Logic Circuit Truth Table
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 9 of 30
A B A.B=Q
0 0 1
0 1 1
1 0 1
1 1 0
Exercise No: 5
Aim:
NAND GATE
Conduct an experiment to Design and simulate logic circuit of NAND gate.
Components:
1. NAND gate - 1 No.
2. Logic switch - 2 Nos
3. Logic Display - 1 No.
4. Out Put Display -1 No.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
The term NAND is a contraction of NOT-AND and implies an AND function with an inverted output.
A NAND gate gives an output “0‟ when both of its inputs are “1”. For all other combinations of input,
it gives an output “1”.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit of NAND gate is designed and simulated. Simulation of the circuit satisfies the truth
table.
Logic Symbol Boolean Equation
A.B=Q
Logic Circuit Truth Table
Govt Polytechnic, Raichur Mechatronics Lab Manual Page 10 of 30
INPUTS OUTPUT
A B A⊕B=Q
0 0 0
0 1 1
1 0 1
1 1 0
Exercise No: 6
Aim:
XOR GATE
Conduct an experiment to Design and simulate logic circuit of XOR gate.
Components:
1. XOR gate - 1 No.
2. Logic switch - 2 Nos
3. Logic Display - 1 No.
4. Out Put Display -1 No.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
The XOR is an abbreviation for Exclusive-OR gate. A XOR gate gives an output “1” when its two
inputs are not equal. It gives an output “0” when its both inputs are same.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit of XOR gate is designed and simulated. Simulation of the circuit satisfies the truth table.
Logic Symbol Boolean Equation
A⊕B =Q
Logic Circuit Truth Table
INPUTS OUTPUT
A B Q
0 0 0
0 1 0
1 0 0
1 1 1
Exercise No: 7
Aim:
COMBINATION OF GATES
BUILDING AND GATE USING THREE NOR GATES
Conduct an experiment to To build AND gate using three NOR gates and simulate the circuit.
Components:
1. NOR gate - 3 Nos
2. Logic switch - 2 Nos
3. Logic Display - 1No
Software Used:
Electronics work bench software, logic gates simulator
Theory:
The logic gates NOR and NAND are considered as universal gates. It appears that to make logic
circuits we require a range of gates. However we can make up all the gates from just one type of gate.
In this exercise we use three NOR gates to obtain the output same as that of an AND gate.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
AND gate is built using three NOR gates and the circuit is simulated. Simulation of the circuit satisfies
the truth table.
Logic Circuit Truth Table
Govt Polytechnic Raichur Mechatronics Lab Manual Page 10 of 30
Govt Polytechnic Raichur Mechatronics Lab Manual Page 11 of 30
INPUTS OUTPUT
A B Q
0 0 0
0 1 1
1 0 1
1 1 1
Exercise No: 8
Aim:
BUILDING OR GATE USING THREE NAND GATES
Conduct an experiment to To build OR gate using three NAND gates and simulate the circuit.
Components:
1. NAND gate - 3 Nos
2. Logic switch - 2 Nos
3. Logic Display - 1 No.
4. Out put Display -1No.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
It appears that to make logic circuits we require a range of gates. However we can make up all the
gates from just one type of gate. In this exercise we use three NAND gates to obtain the output same
as that of an OR gate.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
OR gate is built using three NAND gates and the circuit is simulated. Simulation of the circuit satisfies
the truth table.
Logic Circuit Truth Table
Govt Polytechnic Raichur Mechatronics Lab Manual Page 12 of 30
INPUT OUTPUT
A Q
0 1
1 0
Exercise No: 9
Aim:
BUILDING NOT GATE USING NOR / NAND GATE
Conduct an experiment to To build NOT gate using two NOR/NAND gate and simulate the circuit.
Components:
1. NOR/NAND gate - 1 No.
2. Logic switch - 1 No.
3. Logic Display - 1 No.
4. Out Put Display -1 No.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
It appears that to make logic circuits we require a range of gates. However we can make up all the
gates from just one type of gate. In this exercise we use two NOR/NAND gate to obtain the output
same as that of a NOT gate.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
NOT gate is built using NOR/NAND gate and the circuit is simulated. Simulation of the circuit satisfies
the truth table.
Logic Circuit Truth Table
Govt Polytechnic Raichur Mechatronics Lab Manual Page 13 of 30
Exercise No: 10
Aim:
DE MORGAN’S FIRST THEOREM
Conduct an experiment to Design and simulate a logic circuit to verify De Morgan’s first theorem.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
De Morgan’s first theorem states that “The compliment of sum is equal to the product of individual
compliments”. That is A+B = A.B
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit for De Morgan’s first theorem is designed and simulated. Simulation of the circuit
satisfies the truth table. Hence De Morgan’s first theorem is verified.
Logic Circuit Truth Table
A A+B
B
A.B
INPUTS OUTPUTS
A B A+B A.B
0 0 1 1
0 1 0 0
1 0 0 0
1 1 0 0
Components:
1. NOR gate - 1 No.
2. AND gate - 1 No.
3. NOT gate - 2 Nos
4. Logic switch - 2 Nos
5. Logic Display
- 2 Nos
Govt Polytechnic Raichur Mechatronics Lab Manual Page 14 of 30
Exercise No: 11
Aim:
DE MORGAN’S SECOND THEOREM
Conduct an experiment to Design and simulate a logic circuit to verify De Morgan’s second theorem.
Software Used:
Electronics work bench software, logic gates simulator
Theory:
De Morgan’s second theorem states that “The compliment of product is equal to the sum of individual
compliments”. That is A.B = A + B
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit for De Morgan’s second theorem is designed and simulated. Simulation of the circuit
satisfies the truth table. Hence De Morgan’s second theorem is verified.
Logic Circuit Truth Table
A A.B
B
A+B
INPUTS OUTPUTS
A B ̅�̅̅. ̅
�̅
�̅ +
�̅
0 0 1 1
0 1 1 1
1 0 1 1
1 1 0 0
Components:
1. NAND gate - 1 No.
2. OR gate - 1 No.
3. NOT gate - 2 Nos
4. Logic switch - 2 Nos
5. Logic Display
- 2 Nos
Govt Polytechnic Raichur Mechatronics Lab Manual Page 15 of 30
Exercise No: 12
FLIP FLOPS
S-R FLIP FLOP
Aim: Conduct an experiment to Design and simulate a logic circuit of S-R flip flop.
Components:
1. SR Flip flop - 1 No.
2. Logic switch - 2 Nos
3. Logic Display - 2 Nos
Software Used:
Electronics work bench software, flip flop
Theory:
The flipflop is a basic memory element which is made up of an assembly of logic gates and is a
sequential logic device. The SR flip flop has a “SET” input (S) and a “RESET” input (R). The “S”
input causes the output Q=1 and Q=0. The “R” input causes the out put Q=0 and Q=1. Once the
outputs are established, the wiring of the circuit is maintained until S or R go high.
Procedure:
1. Open CircuitMaker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit of S-R flip flop is designed and simulated. Simulation of the circuit satisfies the truth
table.
Logic Symbol
Logic Circuit
Truth Table
INPUTS OUTPUT
S R Q �̅
0 0 Previous state (Q)
0 1 0 1
1 0 1 0
1 1 Not allowed
Truth Table
Govt Polytechnic Raichur Mechatronics Lab Manual Page 16 of 30
INPUTS OUTPUT
J K Q �̅
0 0 Previous state (Q)
0 1 0 1
1 0 1 0
1 1 Toggle Q �̅
Logic Circuit
Exercise No: 13
J-K FLIP FLOP
Aim: Conduct an experiment to Design and simulate a logic circuit of J-K flip flop.
Components:
1. JK SR Flip flop - 1 No.
2. Logic switch - 3 Nos
3. Logic Display - 2 Nos
Software Used:
Electronics work bench software, flip flop
Theory:
For many applications, the indeterminate state that occurs with SR flip flop when S=1 and R=1 is not
acceptable and in such condition JK flipflop is used. In this flipflop also “J” input causes the output
Q=1 and Q=0. The “K” input causes the out put Q=0 and Q=1. But when both J=1 and K=1 the
outputs are toggled.
Procedure:
1. Open Circuit Maker and start a new file by clicking File New.
2. Select the required components by clicking Devices Browse and place them on the screen.
3. Connect the components to each other by using Wire Tool.
4. Run the Simulation by clicking on Run button.
5. Set the input values as in the truth table and note down the outputs.
6. Stop the Simulation by clicking on Stop button.
Result:
Logic circuit of J-K flip flop is designed and simulated. Simulation of the circuit satisfies the truth
table.
Logic Symbol
Truth Table
Govt Polytechnic Raichur Mechatronics Lab Manual Page 17 of 30
PROGRAMMABLE LOGIC CONTROLLERS
1. Definition
A programmable logic controller, PLC, or programmable controller
is a digital computer used for automation of typically industrial
electromechanical processes, such as control of machinery on factory
assembly lines, amusement rides, or light fixtures. PLCs are used in
many machines, in many industries.
2. Advantage and Disadvantages of PLC
Flexibility: One single Programmable Logic Controller can easily run
many machines.
Correcting Errors: In old days, with wired relay-type panels, any program
alterations required time for rewiring of panels and devices. With PLC
control any change in circuit design or sequence is as simple as retyping
the logic. Correcting errors in PLC is extremely short and cost effective.
Space Efficient: Today's Programmable Logic Control memory is getting
bigger and bigger this means that we can generate more and more contacts,
coils, timers, sequencers, counters and so on. We can have thousands of contact
timers and counters in a single PLC. Imagine what it would be like to have
so many things in one panel.
Low Cost: Prices of Programmable Logic Controllers vary from few
hundreds to few thousands. This is nothing compared to the prices of the
contact and coils and timers that you would pay to match the same things.
Add to that the installation cost, the shipping cost and so on.
Testing: A Programmable Logic Control program can be tested and
evaluated in a lab. The program can be tested, validated and corrected saving
very valuable time.
Visual observation: When running a PLC program a visual operation can
be seen on the screen. Hence troubleshooting a circuit is really quick, easy and
simple.
Govt Polytechnic Raichur Mechatronics Lab Manual Page 18 of 30
3. PLC Applications
1. The batch processes in chemical, cement, food and paper industries which are
sequential in nature, requiring time of event based decisions is controlled by PLCs.
2. In large process plants PLCs are being increasingly used for automatic start up and
shut down of critical equipment. A PLC ensures that equipment cannot be started
unless all the permissive conditions for safe start have seen established. It also
monitors the conditions necessary for safe running of the equipment and trips the
equipment whenever any abnormality in the system is detected.
3. The PLC can be programmed to function as an energy management system for
boiler control for maximum efficiency and safety.
4. For blast furnace charging controls in steel plants
5. For chemical plants process control automation.
6. In automation of a rock phosphate drying and grinding system.
7. Modernization of boiler and turbo generator set.
8. Process visualization for mining application.
9. Criteria display system for power station.
10. As stored programmed automation unit for the operation of diesel generator sets.
11. In Dairy automation and food processing.
12. For a highly modernized pulp paper factory.
13. In automation system for the printing industry.
14. In automation of container transfer crane.
15. In automation of High-speed elevators.
16. In automation of machine tools and transfer lines.
17. In Mixing operations and automation of packaging plants.
18. In fuel oil processing plants and water classification plants.
19. To control the conveyor/classifying system.
4. PLC in Conveyor control System
The simple suitable application is a conveyor system. The
requirements of the conveyor systems are as follows:
1. A programmable logic controller is used to start and stop the motors of the
conveyor belt.
Govt Polytechnic Raichur Mechatronics Lab Manual Page 19 of 30
2. The conveyor system has three segmented conveyor belts. Each
segment is run by a motor.
3. To detect the position of a plate, a proximity switch is positioned at the
segment’s end.
4. The first conveyor segment is turned ON always.
5. The proximity switch in the first segment detects the plate to turn ON the
second conveyor segment.
6. The third conveyor segment is turned ON when the proximity switch detects
the plate at the second conveyor.
7. As the plate comes out of the detection range, the second conveyor is stopped
after 20 secs.
8. When the proximity switch fails to detect the plate, the third conveyor is
stopped after 20 secs.
5. PLC SYSTEM:
Figure shows in block form the four major units of a PLC system and how they
are interconnected. The four major parts of PLC are
1. CENTRAL PROCESSING UNIT(CPU):
The “Brain” of the system of the system, which has three subparts
a. Microprocessor: the computer center that carries out mathematics and logic
operations
Govt Polytechnic Raichur Mechatronics Lab Manual Page 20 of 30
b. Memory: the area of the CPU in which data and information is stored and
retrieved. Holds the system software and user program
c. Power Supply: the electrical supply that converts alternating current (AC)
line voltage to various operational DC values. In the process, the power
supply filters and regulates the voltages to ensure proper computer
operation.
2. PROGRAMMER/ MONITOR: The programmer/monitor is a device used to
communicate with the circuit of the PLC. Hand held terminals, industrial
terminals, and the personal computers exist as PM devices. In a hand held unit
input takes place through a membrane keypad and the display is usually a
Liquid crystal display (LCD). With the industrial terminal are the personal
computer, more complex typewriter type keyboards, and cathode ray tubes
(CRT) are employed.
3. I/O MODULES: The input modules has terminals in to which outside process
electrical signal, generated by sensors or transducers are entered the output
modules has terminal to which the output signals are sent to activate relay,
solenoid, various solid state switching devices, motors, and displays. An
electronic system for connecting I/O modules to remote locations can be added
if needed. The actual operating process under PLC controlled can be thousand
of feet from the CPU and its I/O modules.
4. RACKS AND CHASSIS: the racks on which the PLC parts are mounted and
the enclosure on which the CPU, PM and I/O modules are mounted.
5. PROGRAMMING DEVICES:
PLC programming equipment
exists to allow you to write, edit,
and monitor a program. As well as
perform various diagnostic
procedures. In most cases the
programming device, the Computer,
must be connected to the CPU
Govt Polytechnic Raichur Mechatronics Lab Manual Page 21 of 30
while programs are written. Other PMs, however, allow you to program offline
and then download the program to the PLC CPU.
Three types of programmer also referred as Program loaders are in
common use. At the low end are the hand held, palm-size units with dual-
function keyboards and a liquid crystal display (LCD) Or LED window. At
a user-friendlier level are the full-size keyboards, accompanied by a large
liquid crystal display (LCD) or Cathode Ray Tube (CRT) screen. A Third
programming option exists with software that allows programs to be
developed on IBM- compatible Personal Computers (PCs).
6. PROGRAMMING OF PLC
PROGRAMMING FORMATS:
PLC programming formats differ depending upon the manufacturers.
But experience has shown that when a person learns to program one type of
PLC, he, or she can easily master other PLC systems, even though the
formats differ somewhat.
Some of the factors that vary between formats are nomenclature,
numbering schemes, and screen appearance.
Most Commonly used PLC programming method is Ladder Diagram.
In addition to this several other high-level languages are used to program
PLC. Following are some of this kind, which have received global
recognition.
1. Instruction List
2. Structured Text
3. Function Block Diagram
4. Sequential Function
1. Instruction List (IL): IL is a programming system that consists of a series of
sequential statements, which define a program.
2. Structured Text (ST): ST is a programming system that uses a series of steps and
descriptions to define a program. Structured text uses lots of IF, Else, and
TRUE or FALSE descriptions in its program.
3. Function Block Diagram (FBD): FBD is a programming that uses large function
blocks for portions of programs.
Govt Polytechnic Raichur Mechatronics Lab Manual Page 22 of 30
4. Sequential Function Chart (SFC): SFC is a PLC programming system that uses
vertical and parallel connected blocks and “gates” for the program.
7. RELAY LADDER LOGIC:
The logic you enter into the micro controller makes up a ladder
program. A ladder program consists of a set of instructions used to control a
machine or a process. Ladder logic is a graphical programming language based
on electrical relay diagrams. Instead of having electrical rung continuity,
ladder logic is looking for logical rung continuity. A ladder diagram identifies
each of the elements in an electromechanical circuit and represents them
graphically. This allows you to see how your control circuit operates before
you actually start the physical operation of your system.
PLC programming based on the use of ladder diagrams involves
writing a program in a similar manner to drawing a switching circuit. The
ladder diagram consists of two vertical lines representing the power rails.
Circuits are connected as horizontal lines, i.e. the rungs of the ladder,
between these two vertical lines.
Below table show some of the basic elements used while writing a
ladder diagram,
Element Symbol Used Description
Open
Contact
When the associated Input signal state is “1”, the
contact is “closed”.
if input signal state is “0” the contact is “open”
Closed
Contact
When the associated Input signal state is “0”, the
contact is “closed”.
if input signal state is “1” the contact is “open”
Output
The signal state of this element is “1”, if the
associated input signal is “1”,
otherwise it is “0”
8. PROPER CONSTRUCTION OF PLC LADDER DIAGRAMS:
1. A contact must always be inserted at the beginning of a rung
2. A coil must be inserted at the end of a rung
Govt Polytechnic Raichur Mechatronics Lab Manual Page 23 of 30
3. All contacts must run horizontally, no vertically oriented contacts are allowed
4. The number of contact per matrix(in one rung) is limited – i.e., 11 across by 7
down
5. only one output may be connected to a group of contacts
6. Contacts must be “nested” (a branch circuit programmed within a branch
circuit) properly or, in some PLCs, not at all.
7. Flow must be from left to right
8. Contacts progression should be straight across
9. ILLUSTRATION:
In the following illustration, the electromechanical circuit shows
PB1 and PB2, two pushbuttons, wired in series with an alarm horn. PB1 is
a normally open pushbutton, and PB2 is normally closed. This same
circuit is shown in ladder logic by two contacts wired in series with an output.
Contact I/0 and I/1 are examine-if-closed instructions.
The table below shows how these circuits operate. The table shows
all possible conditions for the electromechanical circuit, the equivalent state
of the ladder logic instructions, and the resulting Output State.
If PB1 is: I/0 state is If PB2 is: I/1 state is Then the Alarm horn is:
Not pushed 0
Not pushed 1 Silent
Not pushed 0 Pushed 0 Silent
Pushed 1 Not
pushed 1 Alarm
Pushed 1 Pushed 0 Silent
Vbbcbbvccjn
Djbnjdsjb;
Govt Polytechnic Raichur Mechatronics Lab Manual Page 24 of 30
LATCHING:
There are often situations where it is necessary to hold a coil energized,
even when the input, which energized it, goes off. The term latch circuit is
used for the circuit used to carry out such an operation. It is self- maintaining
circuit in that, after being energized, it maintains that state
until another input is received. It remembers its last state.
TIMERS:
A timer circuit is specified by stating the interval to be timed and the
conditions or events that are to start and/or stop the timer. They are commonly
regarded as relays with coils which, when energized, result in the closing, or
opening of input contacts after some preset time. Fig shows part of a
program involving a delay-on timer. When there is input, the timer is
energized and starts timing. After some preset time the contacts associated
with the timer close and the output occurs.
10. TYPES OF TIMERS:
1. Timer-On Delay
2. Timer-Off Delay
3. Retentive Timer-On Delay
1. Timer-On Delay
TON Timer On Delay
Timer
Time Base
Preset
Accum
T4:1
1.0
10
00
DN
Govt Polytechnic Raichur Mechatronics Lab Manual Page 25 of 30
Exercise No: 14
Aim:
LADDER DIAGRAM TO REPRESENT LOGIC ‘AND’
Conduct an experiment to To draw the ladder rungs to represent two switches normally open and
both have to be closed for the motor to operate.
Description:
This circuit makes use of two input switches which are normally open. The input switches are
connected in series so that the output occurs only when both the switches are closed, which thus gives
AND logic.
Software Used:
PLC Ladder simulator
Procedure:
1. Construct the circuit diagram as per the requirement using ladder programming elements.
2. Compile the program and simulate the working of the circuit on the monitor.
3. Connect the PLC and switch on the power.
4. Transfer the ladder program to PLC.
5. Run the simulation in PLC.
Result:
The ladder logic program to operate a motor only when both the switches are closed is designed and
tested.
Mnemonic List:
Sl. No. Instruction Operand
1 LD 0000
2 LD 0001
3 OUT 501
4 END -
5 ENDH -
Ladder Diagram:
Govt Polytechnic Raichur Mechatronics Lab Manual Page 26 of 30
Exercise No: 15
Aim:
LADDER DIAGRAM TO REPRESENT LOGIC ‘OR’
Conduct an experiment to To draw the ladder rungs to represent either of the two normally open
switches to be closed for the coil to be energised.
Description:
This circuit makes use of two input switches which are normally open. The input switches are
connected in parallel so that the coil is energized when any one of the switches is closed, which thus
gives OR logic.
Procedure:
1. Construct the circuit diagram as per the requirement using ladder programming elements.
2. Compile the program and simulate the working of the circuit on the monitor.
3. Connect the PLC and switch on the power.
4. Transfer the ladder program to PLC.
5. Run the simulation in PLC.
Result:
The ladder logic program to energize a coil when either of the two switches is closed is designed and
tested.
Mnemonic List:
Sl. No. Instruction Operand
1 LD 0000
2 LD 0001
3 OUT 501
4 END -
5 ENDH -
Ladder Diagram:
Govt Polytechnic Raichur Mechatronics Lab Manual Page 27 of 30
Sl. No. Instruction Operand
1 LD 0000
2 TMR 001#00020
3 LDB T001
4 OUT 501
5 END -
6 ENDH -
Exercise No: 16
TIMER CIRCUIT
Aim: Conduct an experiment to To devise a timing circuit that will switch on for 20s and then switch it off.
Description:
Sometimes it is necessary to switch on a output for a fixed duration of time and then switch it off. This
function is achieved by using a timing circuit. The timing circuit makes use of a timer and a timer
switch associated with it. A normally closed switch is connected in series with it, in order to switch
off the output after a specified time.
Software Used:
PLC Ladder simulator
Procedure:
1. Construct the circuit diagram as per the requirement using ladder programming elements.
2. Compile the program and simulate the working of the circuit on the monitor.
3. Connect the PLC and switch on the power.
4. Transfer the ladder program to PLC.
5. Run the simulation in PLC.
Result:
The ladder logic program to switch on a motor for 20s and then switch it off is designed and tested.
Mnemonic List: Ladder Diagram:
Govt Polytechnic Raichur Mechatronics Lab Manual Page 28 of 30
Sl. No. Instruction Operand
1 LD 0000
2 LDB T002
3 TMR 001#00020
4 LD T001
5 TMR 002#00010
6 OUT 501
7 END -
8 ENDH -
Exercise No: 17 ON AND OFF CIRCUIT
Aim: Conduct an experiment to To devise a timing circuit that will switch on 10s and off 20s and so on.
Description:
This circuit makes use of two timers with one normally open switch and one normally closed switch.
The output gets on and off for the set time.
Software Used:
PLC Ladder simulator
Procedure:
1. Construct the circuit diagram as per the requirement using ladder programming elements.
2. Compile the program and simulate the working of the circuit on the monitor.
3. Connect the PLC and switch on the power.
4. Transfer the ladder program to PLC.
5. Run the simulation in PLC.
Result:
The ladder logic program to switch on a motor for 10s and off 20s and so on is designed and tested.
Mnemonic List: Ladder Diagram:
Govt Polytechnic Raichur Mechatronics Lab Manual Page 29 of 30
Sl.
No. Instruction Operand
1 LD 0000
2 OUT 501
3 LD 501
4 TMR 001#00050
5 LD T001
6 OUT 502
7 LD 502
8 TMR 002#00040
9 LD T002
10 RES 501
11 TMR 003#00010
12 LD T003
13 RES 502
14 END -
15 ENDH -
Exercise No: 18
Aim:
MOTOR-PUMP SEQUENCING CIRCUIT
Conduct an experiment to To devise circuit that can be used to start a motor and then to start a pump
after delay of 50s. Then the motor is switched off 10s before the pump is switched off when the pump
remains on for 50s.
Software Used:
PLC Ladder simulator
Description:
This circuit is an example of sequencing. It works in the following sequence.
1. Switch on the motor
2. After a delay of 50s, switch on a pump.
3. The motor is switched off 40s after the pump is switched on.
4. Then after 10s pump is also switched off.
Procedure:
1. Construct the circuit diagram as per the requirement using ladder programming elements.
2. Compile the program and simulate the working of the circuit on the monitor.
3. Connect the PLC and switch on the power.
4. Transfer the ladder program to PLC.
5. Run the simulation in PLC.
Result:
The ladder logic program to operate motor and pump in a particular sequence is designed and test
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