PRESENTED BY: Chandramaul Sen
Department of Electrical Engineering
GEETA INSTITUTE OF MANAGEMENT AND TECHNOLOGY,
Advance Technology, Chandigarh
Advance Technology, Chandigarh is an ISO 9001:2008
Certified Company deals in the field of Hardware
Development, Embedded Products Development, Security
& Surveillance and Engineers Training Programs.
Advance Technology offer various Technical Education
solutions, Products & Development tools to Engineering
colleges, Universities, research organizations.
Advance Technology has developed a number for private
as well government organizations.
Programmable Logic Controllers
Machine controls, Packaging, Material handling, similar Sequential
task as well as Process control
Advantages of PLC :
They are fast and designed for the rugged industrial environment.
They are attractive on Cost-Per-Point Basis.
These Devices are less Proprietary ( E.g.. Using Open Bus Interface.)
These Systems are upgraded more Capabilities with dedicated PID
and Ethernet Modules.
Disadvantages of PLC :
PLC one time cost is high
To maximize PLC performance a number of IO Modules to be added.
PLC hold only one copy of program.
P L C Components(Hardware)
Central Processing Unit
Central Processing Unit
It is a micro-controller based circuitry. The CPU
consists of following blocks :
Arithmetic Logic Unit (ALU), Program memory
Process image memory (Internal memory of CPU)
Internal timers ,counters and Flags .
CPU performs the task necessary to fulfill the PLC
functions. i.e. Scanning I/O bus traffic control, Program
execution, Peripheral and External device
communication, data handling and self diagnostics.
These modules act as interface between real-time status of process
variable and the CPU.
Analog input module : Typical input to these modules is
4-20 mA, 0-10 V
Ex : Pressure, Flow, Level Tx, RTD (Ohm), Thermocouple
Digital input module : Typical input to these modules is 24 V DC,
115 V AC, 230 V AC
Ex. : Switches, Pushbuttons, Relays, pump valve on off status
These modules act as link between the CPU and the output
devices in the field.
Analog output module : Typical output from these modules is 4-
20 mA, 0-10 V
Ex : Control Valve
Digital output module : Typical output from these modules is 24 V
DC, 115 V AC, 230 V AC
Ex. : Solenoid Valves, lamps, Actuators, Pump valve on off
I/O MODULE SPECIFICATION
ON-STATE INPUT VOLTAGE RANGE
AMBIENT TEMP RATING
INPUT DELAY –
NOMINAL OUTPUT VOLTAGE
MAX O/P CURRENT
ELECTRICAL ISOLATION –
The power supply gives the voltage required for electronics
module (I/O, CPU, memory unit) of the PLC from the line
The power supply provides isolation necessary to protect the
solid state devices from most high voltage line spikes.
As I/O is expanded, some PLC may require additional power
supplies in order to maintain proper power levels.
Advantage of PLC Over Relay
1-More wiring 1-Less wiring
2-Changes difficult 2-Changes easy
3-More power 3-Low power
4-More maintenance 4-Solid state reliability
5-Difficult to expand 5 -Easy to expand
Sense the Input
Process the Logic
Inputs CPU Outputs
Configuration of PLC : Allen Bradley
PLC Programming Standards
Function Block Diagram
Sequential Function Chart
Structured Text Language
PLC : Protocol
• It is a set of rules for data transmission when PLC is
connected to network
• RS-232 (Recommended standard)
• MPI(Multi point Interface)
• DH(Data Highway)
Program of Bottle Filling Plant
Supervisory Control and
It is a purely software package that is positioned on
top of hardware to which it is interfaced, in general
via Programmable Logic Controllers (PLCs), or other
commercial hardware modules.
SCADA systems are used not only in industrial
processes: e.g. steel making, power generation
(conventional and nuclear) and distribution, chemistry,
but also in some experimental facilities such as nuclear
fusion. The sizes of such plants are range from a few
1000 to several 10 thousands input/output (I/O) channels.
One distinguishes two basic layers in a SCADA system: the "client layer"
which caters for the man machine interaction and the "data server layer" which
handles most of the process data control activities.
The data servers communicate with devices in the field through process
controllers. Process controllers, e.g. PLCs, are connected to the data servers
either directly or via networks or field buses that are proprietary (e.g. Siemens
H1), or non-proprietary (e.g. Profibus).
Data servers are connected to each other and to client stations via an Ethernet
LAN. The data servers and client stations are NT platforms but for many
products the client stations may also be W95 machines.