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Presentation On
Programmable Logic Controller
(PLC)
By: -
ROSHIT KADIRU
7TH SEM EE
What Is Programmable Logic Controller?
A programmable Logic Controller (PLC) is a digital
computer used for automation of ...
• Cost effective for controlling complex systems.
• Flexible and can be reapplied to control other systems
quickly and eas...
Architecture of PLC
I
n
p
u
t
M
o
d
u
l
e
O
u
t
p
u
t
M
o
d
u
l
e
Central
Processing Unit
(CPU)
Power
Supply
Program-
ming...
Architecture of PLC
Input Module : It senses the presence or absences of an input signal at each of its
input terminal.
Ou...
Scan Cycle of PLC
Read input
Run
Program
Adjusts
output
The Scan is a
continuous
and sequential
process
• There are three types of PLC.
1. Unitary PLC
Types Of PLC
2. Modular PLC
3. Rack Mounted PLC :
 It contains every feature of a basic system in one box.
They are attached to the machine being controlled.
 Advantages:...
 It s a range of modules that slot together to build up a system.
The basic are the power supply, the main module contain...
 This is similar concept to the modular design but the modules
are on standard cards that slot into a standard rack insid...
What happens when line voltage comes in contact with
the low voltage DC section of PLC?
6
5 4
3
2
18
7
Relay Coil
NO
NC
NO...
What happens when line voltage comes in contact with
the low voltage DC section of PLC?
6
5 4
3
2
18
7
Relay Coil
NO
NC
NO...
Optical Isolation
It means there is no actual electrical
connection between the input device and the
processor. This elimi...
OFF
Micro -
Processor
Input
Signal 1
+5 V
ON
Push Button
Photoelectric Switch
Working of Optical Isolation
LED
Programming Languages of PLC
There are “5” programming Languages in PLC
1. Ladder Diagram (LD)
2. Functional Block Diagram...
Ladder Diagram (LD)
It is a graphical programming language. It is programmed
with simple contacts that simulated the openi...
Ladder Diagram (LD)
Contacts and coils
Examine if closed
Examine if open
It works as normally open switch in a ladder prog...
Ladder Diagram (LD)
Timer
•The Timer On Delay instruction begins to count time base intervals
when rung conditions become ...
Ladder Diagram (LD)
Counter
•Increments the accumulated value at each false to true transition
and retains the accumulated...
AND operation using Ladder Diagram (LD)
(
(
Switch 1 Switch 2 Light
Switch 1 Switch 2
OFFON OFFON
Light
Switch
1
Switch
2
...
Example of Forward and Reverse motor starter
Example’s Ladder Diagram (LD)
Example’s Ladder Diagram (LD)
(
(
(
(
M1
M2
Forward
M1
M1
M2
Reverse
Stop
M2
Forward Reverse
Stop
Normally Open
Push butto...
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Plc example presentation

  1. 1. Presentation On Programmable Logic Controller (PLC) By: - ROSHIT KADIRU 7TH SEM EE
  2. 2. What Is Programmable Logic Controller? A programmable Logic Controller (PLC) is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures.
  3. 3. • Cost effective for controlling complex systems. • Flexible and can be reapplied to control other systems quickly and easily. • Computational abilities allow more sophisticated control. • Trouble shooting aids make programming easier and reduce downtime. • Reliable components make these likely to operate for years before failure. • Small physical size, so shorter project time. •Ease in documentation. Advantages of PLC
  4. 4. Architecture of PLC I n p u t M o d u l e O u t p u t M o d u l e Central Processing Unit (CPU) Power Supply Program- ming Device Push Button Push Button Light Programming Device
  5. 5. Architecture of PLC Input Module : It senses the presence or absences of an input signal at each of its input terminal. Output Module : The output module operates the opposite manner from the input signal. A DC signal from the CPU is converted through each module section to a usable output voltage. Central Processing Unit (CPU) : It is the brain of every computer. CPU carries out arithmetic and logical operations. Programming Device : A programming device is a computer in which programming is done and then by using data cables the program is downloaded into the PLC. For connecting to the PLC “RC-232C” cable is used. RS-232C Cable
  6. 6. Scan Cycle of PLC Read input Run Program Adjusts output The Scan is a continuous and sequential process
  7. 7. • There are three types of PLC. 1. Unitary PLC Types Of PLC 2. Modular PLC 3. Rack Mounted PLC :
  8. 8.  It contains every feature of a basic system in one box. They are attached to the machine being controlled.  Advantages: 1. Less scanning time 2. Fixed versions are usually small, have less memory so cost in less . 3. Less troubleshooting time so less downtime.  Disadvantages : 1. A limited number of inputs and outputs. 2. It is not suited for future expansion. 3. If part of the unit fails, it will take much time and effort to repair, and the entire unit may need replacing. Unitary PLC
  9. 9.  It s a range of modules that slot together to build up a system. The basic are the power supply, the main module containing the CPU, the input and output module.  Advantages: 1. Great flexibility in choice of modules. Modules can be easily installed or removed without affecting other modules 2. The main advantage is that more Input and output terminals can be expanded.  Disadvantages : 1. Scanning time increases with the increase in input and output modules. Modular PLC
  10. 10.  This is similar concept to the modular design but the modules are on standard cards that slot into a standard rack inside a cabinet. These are flexible and allow expansion of the system. Rack Mounted PLC
  11. 11. What happens when line voltage comes in contact with the low voltage DC section of PLC? 6 5 4 3 2 18 7 Relay Coil NO NC NO NC 24 V 230 V Plug in base of relay PLC
  12. 12. What happens when line voltage comes in contact with the low voltage DC section of PLC? 6 5 4 3 2 18 7 Relay Coil NO NC NO NC 24 V 230 V Plug in base of Relay PLC
  13. 13. Optical Isolation It means there is no actual electrical connection between the input device and the processor. This eliminates any possibility of the input line voltage from coming in contact with and damaging the low voltage DC section of the processor. It prevents any unwanted voltage from the i/o section of the processor.
  14. 14. OFF Micro - Processor Input Signal 1 +5 V ON Push Button Photoelectric Switch Working of Optical Isolation LED
  15. 15. Programming Languages of PLC There are “5” programming Languages in PLC 1. Ladder Diagram (LD) 2. Functional Block Diagram (FBD) 3. Structured Text (ST) 4. Instruction List (IL) 5. Sequential Function Chart (SFC)
  16. 16. Ladder Diagram (LD) It is a graphical programming language. It is programmed with simple contacts that simulated the opening and closing of relays it has been expanded to include function such as counters, timers, shift registers and math operation.
  17. 17. Ladder Diagram (LD) Contacts and coils Examine if closed Examine if open It works as normally open switch in a ladder program. If it is ON, the contact will close and allow power (logic) to flow from left to right. If the status is OFF (logical 0), the contact is Open, power (logic) will NOT flow from left to right. It works as normally closed switch in a ladder program, and it works exactly opposite to that of the examine if closed. Normally open coil This can be used to represent any discrete output from the control logic. When "solved" if the logic to the left of the coil is TRUE, the referenced output is ON (logical 1).
  18. 18. Ladder Diagram (LD) Timer •The Timer On Delay instruction begins to count time base intervals when rung conditions become true. As long as rung conditions remain true, the timer adjust its accumulated value (ACC) each evaluation until it reaches the preset value (PRE). The accumulated value is reset when rung conditions go false, regardless of whether the timer has timed out. Timer On Delay Timer T4:1 Time Base 1.0 Preset 100 Accum 0 TON ( ( ( ( EN DN
  19. 19. Ladder Diagram (LD) Counter •Increments the accumulated value at each false to true transition and retains the accumulated value when the instruction goes false or when power cycle occurs. •The CTU is an instruction that counts false to true transition. When this transition happens the accumulated value is incremented by one count. •A CTU accumulation is reset by the RES instruction. Count Up Counter C3:0 Preset 10 Accum 0 CTU ( ( ( ( CU DN
  20. 20. AND operation using Ladder Diagram (LD) ( ( Switch 1 Switch 2 Light Switch 1 Switch 2 OFFON OFFON Light Switch 1 Switch 2 Output 0 0 0 1 0 0 0 1 0 1 1 1 Truth Table
  21. 21. Example of Forward and Reverse motor starter
  22. 22. Example’s Ladder Diagram (LD)
  23. 23. Example’s Ladder Diagram (LD) ( ( ( ( M1 M2 Forward M1 M1 M2 Reverse Stop M2 Forward Reverse Stop Normally Open Push button Normally Open Push button Normally Closed Push button

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