Block Diagram Of PLC. 1) CPU 2) INPUT Module 3) OUTPUT Module 4) Power Supply 5) Communication Device.

1. Block Diagram of PLC
&
Components of PLC

2. Block Diagram of PLC
Programming
Communication
Device
Central
Processing
Unit (CPU)
Memory
Program
Power Supply
INPUT
Circuit
(Field Area)
OUTPUT
Circuit
(Field Area)
Optical
Isolation
Optical
Isolation

3. Components of PLC
 CPU(Central Processing unit)
 INPUT Module
 OUTPUT Module
 Power Supply
 Programming Device

4. Components of PLC
 CUP(Central Processing unit):-
• CPU module has a central processor, ROM & RAM memory.
• ROM memory includes operating system, driver and application
program. RAM memory is used to store programs and data.
• CPU is the brain of PLC with an octal or hexagonal
microprocessor. Being a microprocessor based CPU, it replaces
timers, relays, and counters.
• Two types of processors as a single bit or word processor can be
incorporated with a PLC.
• CPU reads the input data from sensors, process it and finally the
command to controlling devices.

5. Components of PLC
CPU consist of following blocks
• ALU(Arithmetic Logic Unit)
• Programming memory.
• Process image memory.
• Internal timer and counter.
• Flags or status bit filter.
• CPU required 5v.

6. Components of PLC
INPUT MODULE:-
• Input module act as an interface between the field control input and the CPU
voltage/current generated by the sensors,transducer,limit switch,push
button,etc.
• Input module converts the field signal into standard control signal for processing
by the PLC
• The input module of PLC does four main functions.
1. Input module interface receives the signal from process devices at 220 V AC
2. Converts the input signal to 5 V DC that can be used by PLC
3. Isolator block is used to isolate/prevent PLC from undergoing fluctuation
4. After which the signal is sent to the output end i.e the PLC

7. Components of PLC
OUTPUT Module:-
 Output Module acts as link between the CPU and the output devices located in
the field devices could be relays,contaector,lamps,motorized actuators, solenoid
valves,etc.These device actually control the process.

8. Power Supply:-
 This module is used to provide the required power to the whole
PLC system.
 It converts the available AC power to DC power which is required
by the CPU and I/O module. PLC generally works on 24V DC
supply and Rack type PLC work on 230/220Vac. Few PLC uses
an isolated power supply.

9. Components of PLC
Programming Device:-
 A personal computer(PC) is the
most commonly used programming
device.The software allows users to
create,edit,store and troubleshoot
programs.
 This is show pitchure id
programming cable Rs-232 and
Ethernet cabl for Programming
cable
RS-232 Cable
Ethernet Cable

10. Next Video Topic
 Types of PLC.

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