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Road Map
IntroductionBasic PLC components
Introduction to STEP 7 LITE
Programming PLC and Ladder logicExercises
SCADA
Future scope
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Introduction
A digitally operating electronic apparatus
which uses a programmable memory for
implementing specific functions such as :
Logic sequencing
Timing
Counting
Arithmetic controlthrough digital or analog
input/output modules
Invented in 1968 as a substitute for hardwired relay panels
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Purpose of PLC & its
functionsInitially designed to replace relay logic
boards
Accepts input from a series of switches
Sends output to devices or relays
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Functions
On-off control,Sequential control,
Feedback control, and
Motion control
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Basic PLC components
I
N
P
U
T
S CPU
O
UT
P
U
T
S
POWER
SUPPLY
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Power Supply
Every PLC has an external or internalIsolated Power Supply.
Isolated Power Supplies can have more
than one isolated output.
Normally Power supplies are high voltage.
Typically 24 Volts for industrial PLCs.
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INPUTS & Outputs
These are the physical connections from the real
world to the PLC.Inputs can be limit switches, push buttons, andsensors, anything that can "switch" a signal on or off.
Outputs are solenoids, lamps, contactors, relays etc,.
The number of DI/Os can be increased by addingadditional DI/O
modules
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CPU
CPU module mainly classified into
three different parts based on their
operation.
Processor
program memory
serial communication ports
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Scan cycle of PLC
House keeping I/P scan
O/P scan Program scan
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STEP 7 LITE
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STEP 7 LITE
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Programming PLC
FBD (Function block diagram)LD (Ladder diagram)
ST (Structured text, similar to the Pascal
programming language)IL (Instruction list, similar to assembly
language)
SFC (Sequential function chart).
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Virtual relay components
Virtual relay components
Virtual relay components
Power
Rail
Ground
Rail
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Exercises
Direct online starterSequential switching of motors
Fan control unit
Tank level controllerTraffic light control
Bottling Plant simulation
V Y
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SUPERVISORYCONTROL AND DATA
ACQUISTION (SCADA)
SCADA refers to combination of telemetryand Data acquisition. It consist of:
Collecting data
Transferring it back to control site
Carrying out necessary analysis and control
Displaying data on operator screens
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TELEMETRY
It is the technique used in transmitting and
receiving information or data over a medium.
Information can be Voltage, speed, level,
temp, flow etc. Data is transmitted to another
location through cables, Telephone, radio.Information may come from multiple
locations.
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DATA ACQUISTION
It is method used to access and control
information from equipment being
controlled and monitored. The data
accessed is then forwarded on to a
telemetry system fro transfer to differentsites.
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Future scope
Study of :
Interrupts
Counters
Communication Protocol:Profibus
How to use communications to
communicate with other PLCs,smart actuators and sensors, etc
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THANK U
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