Programmable logic controllers (PLCs) and supervisory control and data acquisition (SCADA) systems are commonly used for industrial automation and process control. PLCs control industrial machinery through configurable input and output interfaces and user-programmed logic. SCADA systems run on PCs connected to PLCs and other devices to monitor entire industrial operations through graphical interfaces. Together, PLCs and SCADA enable real-time monitoring and control of industrial processes from remote locations.

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LEVEL 1
PLC
( Programmable logic Controller )
SCADA
(Supervisory Control and Data Acquisition)

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 INTRODUCTION OF PLC
Programmable logic controllers (PLCs) have been an integral part of factory
automation and industrial process control for decades. PLCs control a wide
array of applications from simple lighting functions to environmental system
chemical processing plants.
These systems perform many functions ,providing a variety of analog and
digital input and output interfaces; signal processing; data conversion; and
various communication protocols. All of the PLC's components and functions
are centered around the controller, which is programmed for a specific task.
The basic PLC module must be sufficiently flexible and configurable to meet
the diverse needs of different factories and applications .Input stimuli(either
analog or digital) are received from machines, sensors, or process events in
the form of voltage or current.
The PLC must accurately interpret and convert the stimulus for the CPU
which ,in turn, defines a set of instructions to the output systems that
control actuators on the factory floor or in another industrial environment.
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PLC: A PROGRAMMABLE LOGIC CONTROLLER
A Programmable Logic Controller, or PLC, is more or less a small computer with a
built-in operating system (OS).This OS is highly specialized to handle in coming
events in real time, or at the time of their occurrence.
The PLC has input lines where sensors are connected to notify upon events (e.g.
temperature above / below a certain level, liquid level reached, position etc.),
and output lines to signal any reaction to the incoming events ( e.g. start an
engine, open / close a valve, etc.).
The system is user programmable. It uses a language called "Relay Ladder“ or
RLL (Relay Ladder Logic). The name of this language implies that the control
logic of the earlier days, which was built from relays, is being simulated
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 IMPORTANCE OF PLC
The PLC is primarily used to control machinery. A program is written for the PLC
which turns on and off outputs based on input conditions and the internal
program. In this aspect, a PLC is similar to a computer. However, a PLC is
designed to be programmed once, and run repeatedly as needed.
In fact, a crafty programmer could use a PLC to control not only simple devices
such as a garage door opener, but their whole house, including switching lights
on and off at certain times, monitoring a custom built security system, etc.
Most commonly, a PLC is found inside of a machine in an industrial environment.
A PLC can run an automatic machine for year require little human intervention.
They are designed to with stand most harsh environments.
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SAMPLE PLC
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PLC ARCHITECTURE

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MAIN COMPONENTS OF PLC
POWER SUPPLY
Provides the voltage needed to run the primary PLC components
 I/O MODULES
Provides signal conversion and isolation between the internal logiclevel
signals inside the PLC and the field’s high level signal.
 PROCESSOR
Provides intelligence to command and govern the activities of the entire
PLC systems.
 PROGRAMMING DEVICE
Used to enter the desired program that will determine the sequence of
operation and control of process equipment or driven machine.
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OPERATION OF PLC
Input scan: (checking the status of inputs)
If there are no problems, PLC will copy all the inputs and
copy their values into memory.
Logic solve/scan: (executing a program)
Using inputs, the ladder logic program is solved once and
outputs are updated.
Output scan:(Updating the status of output While solving
logic the output values are updated only in memory when
ladder scan is done, the outputs will be updated using
temporary values in memory.
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Ladder logic
The ladder logic is the oldest programming language for PLC.
 Ladder diagram doesn’t include power supply
 Every line of ladder diagram is called rung.
 There should be at least one output on every rung.
 Main symbols used in ladder programming
Comparison of relay and PLC terminology
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AND GATE OR GATE

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Ladder logic to Start a motor
X1 –Start command
X2 –Stop command
Y1 – Motor ON contactor
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INTRODUCTION OF SCADA
SCADA(Supervisory Control and Data Acquisition)
Now a days automation system contains PLCs and SCADA software. PLC & SCADA
combination has advantages in better monitoring and control of the plant and also it
provide have access to the information the way operator want. SCADA enables
engineers ,supervisors, managers and operators to view and interact with the
workings of entire operations through graphical representation of their production
process.
SCADA runs on a PC and is generally connected to various PLCs and other peripheral
devices. It enables us to generate applications for the most demanding requirements
of plant engineers, operators, supervisors and managers tailored precisely to the
needs of each plant. SCADA constantly gathers data from the plant in real-time,
stores and processes it in the database, evaluates and generates alarms, displays
information to plant operators, supervisors and managers and can issue instructions
to PLCs on the plant floor
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SCADA
(SUPERVISORY CONTROL AND DATA ACQUISITION)
SCADA is a system operating with coded signals over communication
channels so as to provide control of remote equipment (using typically one
communication channel per remote station). The supervisory system may
be combined with a data acquisition system by adding the use of coded
signals over communication channels to acquire information about the
status of the remote equipment ford is play or for recording functions. It is
a type of industrial control system (ICS). Industrial control systems are
computer-based systems that monitor and control industrial processes that
exist in the physical world. SCADA systems historically distinguish
themselves from other ICS systems by being large- scale processes that
can include multiple sites, and large distances.
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SCADA(SUPERVISORY CONTROL AND DATA ACQUISITION)
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FUNCTIONALITY OF SCADA
A Historian is a software service which accumulates time-stamped data,
Boolean events, and Boolean alarms in a database which can be queried or
used to populate graphic trends in the HMI. The historian is a client that
requests data from a data acquisition server.
A supervisory (computer) system, gathering (acquiring) data on the
process and sending commands (control) to the SCADA system.
Communication infrastructure connecting the supervisory system to the
remote terminal units.
Various process and analytical instrumentation
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APPLICATION
Wherever automation is desired the PLCs are best
suited to meet the task.
Few examples of industries where PLCs are used :
1) Robots manufacturing and control
2) Car park control
3) Train control station system
4) Food processing
5) Materials handling
6)Machine tools
7)Conveyer system etc.
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ADVANTAGES OF PLC & SCADA
 Reliability.
 Flexibility in programming and reprogramming.
 Cost effective for controlling complex systems.
 Small physical size, shorter project time.
 High speed of operation.
 Ability to communicate with computer systems in the plant.
 Ease of maintenance /troubleshooting.
 Reduced space.
 Energy saving.
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THANKING YOU
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