Manda Institute of Technology Raisar,
EC IV Year
What is Programmable Logic Controller
A PLC is a digital operating electronic apparatus which uses a
programmable memory for internal storage of instruction for
implementing specific function such as logic, sequencing, timing,
counting and arithmetic to control through analog or digital
input/output modules various types of machines or process.
In 1968, a group of engineers from General Motors
developed the concept of PLC with an initial specification.
The PLC must be:
i . Easy to program.
ii. Not need rewiring the control system if change
iii. Smaller in size, cheaper and high reliability.
iv. simple construction and low maintenance
v. Cost- competitive
analog inputs / outputs
Major Components of a Common PLC
Leading Brands Of PLC
Klockner & Mouller
Leading Brands Of PLC
Areas of Application
Manufacturing / Machining
Food / Beverage
Petrochemical / Chemical
- it covers units with up to 128 I/O’s and memories up to 2
- these PLC’s are capable of providing simple to advance
levels or machine controls.
2. MEDIUM - have up to 2048 I/O’s and memories up to 32 Kbytes.
- the most sophisticated units of the PLC family. They have
up to 8192 I/O’s and memories up to 750 Kbytes.
- can control individual production processes or entire plant.
Tank Used To Mix Two Liquids
Introduction (What Is SCADA?)
Supervisory Control And Data Acquisition is an Industrial
To run a Process Control Network (PCN).
Monitors and controls industrial plant/ equipment.
E.g. water, energy, fuel, telecommunications.
Coordinate data transfer between Remote Terminal Units (RTUs) &
Display information to operators.
Sensors, devices to control.
Remote Terminal Units.
RTU Vs. PLC
Equipment needed to transfer data to and from
Central Monitoring Station
Collecting information gathered by the remote stations to
generate the necessary action
Disadvantages Of Relay Systems
Relays used only for on/off control.
Complicated control systems
System takes up much floor and space.
Control relays are power- hungry, heat
Any change in control program requires the
rewiring of relays.
For complicated control systems, it is difficult to
troubleshoot and locate the faults.
Advantages Of SCADA systems
Easily programmed or reprogrammed
Easy maintained (self diagnostic).
Capability to do arithmetic function.
The ability to communicate with other controller or a master host
PLCs. were able to move past simple on/off control to more complex
schemes as PID control.
Applications Of SCADA
Almost every business in the manufacturing sector and many in
the service sector
Bottling and Canning