2. MODULE CONTENTS
Identifying electronic devices
Analyse sensors and transducers
Apply pneumatic and hydraulic systems.
Analyse actuation systems
Analyse programmable logic controllers
3. Name types of electronic devices
Select electronic devices
Describe electronic devices
Practice to use electronics devices
Define sensors
Define transducers
Identify various types of sensors and transducers
Describe application of sensors and transducers
Module descriptions
4. Describe hydraulic systems
Describe pneumatic systems
Describe the maintenance of electronic systems
Describe the maintenance of pneumatic and hydraulic
systems
Describe the term actuating system
Identify parts of an actuating system
Describe the working principles of actuating systems
Describe the maintenance for actuating systems
Module descriptions
5. Identify programmable logic controllers
Define programmable logic controllers
Describe the working principles of programmable
controllers
Describe the maintenance for programmable
controllers
Module descriptions
7. AUTOMATION
The dictionary defines Automation as “the technique of
making an apparatus, a process, or a system operate
automatically.”
OR Automation is defined as "the creation and application of
technology to monitor and control the production and delivery
of products and services”.
In other words, Automation or automatic control, is the use of
various control systems for operating equipment such as machinery,
processes in factories, boilers and heat treating ovens, switching on
telephone networks, steering and stabilization of ships, aircraft and
other applications and vehicles with minimal or reduced human
intervention, with some processes have been completely
automated.
8. Automation has been achieved by various means
including;
mechanical,
Hydraulic,
pneumatic,
electrical,
electronic devices and
computers, usually in combination.
Automation…
9. Complicated systems, such as modern factories,
airplanes and ships typically use all these combined
techniques.
The benefit of automation include labor savings,
savings in electricity costs, savings in material costs,
and improvements to quality, accuracy and precision.
Automation…
10. ADVANTAGES OF AUTOMATION
1: High productivity
Although many companies hire hundreds of production workers for a up to three
shifts to run the plant for the maximum number of hours, the plant still needs to
be closed for maintenance and holidays. Industrial automation fulfills the aim of
the company by allowing the company to run a manufacturing plant for 24 hours
in a day 7 days in a week and 365 days a year. This leads to a significant
improvement in the productivity of the company.
11. ADVANTAGES…
2: High Quality
Automation alleviates the error associated with a human being.
Further, unlike human beings, robots do not involve any fatigue,
which results in products with uniform quality manufactured at
different times.
3: High flexibility
Adding a new task in the assembly line requires training with a
human operator, however, robots can be programmed to do any
task. This makes the manufacturing process more flexible.
12. ADVANTAGES…
4: High Information Accuracy
Adding automated data collection, can allow you to collect
key production information, improve data accuracy, and
reduce your data collection costs. This provides you with the
facts to make the right decisions when it comes to reducing
waste and improving your processes.
5: High safety
Industrial automation can make the production line safe for
the employees by deploying robots to handle hazardous
conditions.
14. Three components of an automated system:
Power
A program of instructions
A control system to carry out the instructions
There are various control systems used to do the automation they are
Programable Logic Controller –plc
Numerical Control – CNC
and industrial control system.
These control systems are combined with certain computer-aided
technologies so that industrial process control can be done very easily.
So basically automation can be considered as the technology which has
mechanical electronics and computer-based system to do its operation.
Automation…
15. Automation…
Three BasicTypes of Automation
Fixed automation - the processing or assembly steps and their sequence are
fixed by the equipment configuration
Programmable automation - equipment is designed with the
capability to change the program of instructions to allow
production of different parts or products
Flexible automation - an extension of programmable
1/30
17. Automation…
Features of Fixed Automation
High initial investment for specialized equipment
High production rates
The program of instructions cannot be easily changed because it is fixed by
the equipment configuration
Thus, little or no flexibility to
accommodate product variety
18. Automation…
Features of Programmable Automation
High investment in general purpose equipment that can be
reprogrammed
Ability to cope with product variety by reprogramming the
equipment
Suited to batch production of different
product and part styles
Lost production time to reprogram
and change the physical setup
Lower production rates than fixed
automation
19. Automation…
Features of Flexible Automation
High investment cost for custom-engineered equipment
Capable of producing a mixture of different parts or products without lost
production time for changeovers and reprogramming
Thus, continuous production of different part or product styles
Medium production rates
20. Automation…
COMPONENTS FOR PLC SYSTEMS IN AUTOMATION
i. Input
ii. Output
iii. Central processing Unit - CPU
iv. Memory
v. Power supply
vi. Instructions/Program data
vii. Programming device and
Interface
21. The general classification of PLC based
upon the number of inputs and outputs is
Fixed type PLC
Modular type PLC
Rack type PLC
Types of PLCs
22. Fixed type PLC: In this type of PLC all the components of the PLC
are as a single unit. The number of I/O supported by the PLC is
decided by the manufacturer and cannot be changed. This type
of PLC can support a small number of I/Os.
Modular Type PLC: In modular type PLC the number of I/Os can
be increased by the addition of modules to the existing PLC. In
modular type PLC the number of I/O supported can be increased
to few hundreds by adding I/O
modules.
Rack Type PLC: In rack type PLC all the components of the PLC
are as separate modules and are assembled to form one unit by
mounting the individual components on a rack. This PLC can
support up to thousands of I/Os.
Types of PLCs…
23. Automation…
HARDWARE COMPONENTSFOR AUTOMATION
i. Sensors
ii. Actuators
iii. Interface devices
iv. Process controllers - usually computer-based devices such as
a programmable logic controller -PLC
INPUT
The stimulus or excitation applied to a control system from
an external source in order to produce the output is called input.
24. Automation…
OUTPUT
The actual response obtained from a system is called output.
SYSTEM
A system is an arrangement or a combinationof different physical
components connected or related in such a manner so as to form an
entire unit to attain a certain objective.
25. Automation…
CONTROL
It means to regulate , direct or command a system so that
the desired objective is attained
CONTROL SYSTEM
It is an arrangement of different physical elements connected in
such a manner so as to regulate, direct or command itself to
achieve a certain objective.
26. Automation…
Types of Control
devices: Examples of Control Devices
Rotary drum switch
Limit switch
Electromechanical Counter
Fuses
Control Transformers
Motor Starter
Solenoid Valves
Pneumatic plunger timers
etc
Mechanical control
Pneumatic control
Electromechanical
control
Electronic control
Computer control
27. Automation…
Classification of control system
Open loop control system
In general control systems are classified into two categories
as open loop (no feedback)and closed loop(with feedback).
Closed loop control system
28. Automation…
DIFFERENCE BETWEEN OPEN LOOP & CLOSED LOOP SYSTEM
Comparison Open Loop System Closed Loop System
Definition
The system whose control action is
free from the output
In closed loop, the output depends
on the control action of the system.
Other Name Non-feedback System Feedback System
Components Controller and Controlled Process.
Amplifier, Controller, Controlled
Process, Feedback.
Construction Simple Complex
Reliability Non-reliable Reliable
Accuracy Depends on calibration Accurate because of feedback.
Stability Stable Less Stable
Optimization Not-Possible Possible
Response Fast Slow
Calibration Difficult Easy
System Disturbance Affected Not-affected
Linearity Non-linear Linear
Examples
Traffic light, automatic washing
machine, immersion rod, TV remote
etc.
Air conditioner, temperature control
system, speed and pressure control
system, refrigerator, toaster.
30. CONTENTS
What is PLC?
History of PLC
Major components of PLC
Operational sequence of PLC
Ladder logic
Example of starting and stopping of a motor
Advantages
Disadvantages
Application
31. WHAT IS PLC ?
PLC is a digital computer designed for multiple inputs
and output arrangements, extended temperature ranges,
immunity to electrical noise, and resistance to vibration
and impact. A PLC is an example of a real time system.
Various Brands ofPLCs
Allen Bradley
Siemens
Modicon
Mitshubishi
GE Fanuc
Omron
USA
Germany
France
Japan
USA
Japan
32. HISTORY OF PLC
PLC was introduced in late 1960’s
First commercial & successful Programmable Logic Controllers
was designed and developed by Modicon as a relay replacer for
General Motors.
Earlier, it was a machine with thousands of electronic parts.
Later ,in late 1970’s,the microprocessor became reality &
greatly enhanced the role of PLC permitting it to evolve form
simply relay to the sophisticated system as it is today.
33. 33
Major Components of a Common PLC
PROCESSOR
POWER
SUPPLY
I M
N O
P D
U U
T L
E
O M
U O
T D
P U
U L
T E
PROGRAMMING
DEVICE
From SENSORS
Pushbuttons,
contacts,
limit switches,
etc.
To
OUTPUT
Solenoids, contactors,
alarms
etc.
34. 34
Major Components of a Common PLC
POWER SUPPLY
Provides the voltage needed to run the primary PLC components
I/O MODULES
Provides signal conversion and isolation between the internal
logic- level 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.
35. PLC OPERATION SEQUENCE
1)Self test: Testing of its own hardware and software for faults.
2)Input scan: If there are no problems, PLC will copy all the
inputs and copy their values into memory.
3)Logic solve/scan: Using inputs, the ladder logic program is
solved once and outputs are updated.
4)Output scan: 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.
Self test
Input scan
Logic scan
Output
scan
36. 36
Major Components of a Common PLC…
Processor : The processor (CPU) scans the status of the input
peripheral , examines the control logic to see what action to take ,
and then execute the appropriate output response
Memory : the control program and the peripheral status are stored
in the memory
ROM( Read Only Memory )
RAM (Random Access Memory),
PROM (Programmable Read Only Memory),
EEPROM (Electric Erasable Programmable ROM),
EPROM (Erasable Programmable Read Only Memory),
EAPROM (Electronically Alterable Programmable
37. 37
Major Components of a Common PLC…
Input/Output :
modular plug-in periphery
Ac voltage input and output
Dc voltage input and output
Low level analog input
High level analog input and output
Special purpose modulas
Power supply : Ac power(Live(L) and Neutral(N))
Peripherals : Hand-Held Programmer ( HHP)
CRT programmer
Operetor console
Printer
Simulator
EPROM loader
Graphics processor
HAND HELD PROGRAMMER
46. PROGRAMMING LANGUAGES OF PLC
Most common languages encountered in PLC programming are:
1) Ladder Logic Diagram(LD)
2) Functional Block Diagram(FBD)
3) Sequential Function Chart(SFC)
4) Structured Text(ST)
5) Instruction List(IL)
47. LADDER LOGIC DIAGRAM -LD
A ladder diagram (also called contact symbology) is a
means of graphically representing the logic required in a
relay logic system. The ladder logic is the oldest
programming language for PLC. It is well suited to express
Combinational logic.
The main ladder logic symbols represent the elements :
Make contact Or examine if Closed
Break contact Or examine if Opened
Relay coil
48. A
R1
PB1 PB2
R1
R1
start emergencystop
Rail
Rung
1) Relay,
2) Timer and counter,
3) Program control,
4) Arithmetic,
5) Data manipulation,
6) Data transfer, and
7) Others, such as
sequencers.
Hint : Relay , timer and counter instructions
are the most fundamental because they
correspond to what is on a ladder diagram
and are available on all PLCs so we limit our
lesson to them
PLC Ladder Diagram INSTRUCTIONS
49. A Relay consists of two parts, the coil and the contact(s).
Contacts:
a. Normally open -| |-
b. Normally closed -|/|-
c. Positive transition sensing -|P|-
d. Negative transition sensing -|N|-
Coil:
a. Coil -( )-
b. negative coil -(/)-
c. Set Coil -(S)-
d. Reset Coil -(R)-
PLC Ladder Diagram INSTRUCTIONS…
50. PLC Ladder Diagram INSTRUCTIONS…
Coil:
e. Retentive memory Coil -(M)-
f. Set retentive memory Coil -(SM)-
g. Reset retentive memory Coil -(RM)-
h. Positive Transition-sensing Coil -(P)-
h. Negative Transition-sensing Coil -(N)-
Set coil latches the state, reset coil deenergize the set coil.
retentive coil retain the state after power failure.
Relay…
51. TIMERS AND COUNTERS
Timers:
a. Retentive on delay -(RTO)-
b. Retentive off delay -(RTF)-
c. Reset -(RST)-
Counter:
a. Counter up-(CTU)-
b. Counter down -(CTD)-
c. Counter reset -(CTR)-
PLC Ladder Diagram INSTRUCTIONS…
53. AND Gate
OR Gate
NOT Gate
NAND Gate
NOR Gate
EX-OR Gate
EX-NOR Gate
LOGIC GATES USING PLC LADDER
This is the list of all logic gates which are very important for
Basic Programming
To understand these functions is important for the basic level of
PLC programming.
54. 1. AND Gate
AND logic gate is the basic multiplication logic gate. The output will turn ON
only if all the inputs will be ON.
AND Gate logic expression: Y = A * B = A.B
PLC Ladder Logic of AND Gate
Implementation of Logic Gates using PLC Program
55. 2. OR Gate
OR logic gate is the basic addition logic gate. The output will turn ON if any of
the inputs will be ON.
OR Gate logic expression: Y = A + B
PLC Ladder Logic of OR Gate
Implementation of Logic Gates using PLC Program…
56. 3. NOT Gate
NOT logic gate is the inverse logic gate. When the input is ON, the output will
be OFF and when the input is OFF, the output will be ON.
PLC Ladder Logic of NOT Gate
Implementation of Logic Gates using PLC Program…
57. 4. NAND Gate
NAND logic gate is the combination of AND and NOT logic gates, Output will
only be OFF when all the inputs will be ON.
PLC Ladder Logic of NAND Gate
Implementation of Logic Gates using PLC Program…
58. 5. NOR Gate
NOR logic gate is the combination of OR and NOT logic gates, Output will only
be ON when all the inputs will be OFF.
PLC Ladder Logic of NOR Gate
Implementation of Logic Gates using PLC Program…
59. 6. EX-OR Gate
EX-OR logic gate is the combination of AND, NOT and OR gate.
PLC Ladder Logic of EX-OR Gate
Implementation of Logic Gates using PLC Program…
60. 7. EX-NOR Gate
EX-NOR logic gate is the combination of AND, OR and NOT gate.
PLC Ladder Logic of EX-NOR Gate
Implementation of Logic Gates using PLC Program…
61. LADDER LOGIC FOR BASIC GATES
A B Logic(Y)
OFF
OFF
ON
ON
OFF
ON
OFF
ON
OFF
OFF
OFF
ON
AND Gate
A B Y
A B Logic(Y)
OFF
OFF
ON
ON
OFF
ON
OFF
ON
OFF
ON
ON
ON
A
B
Y
OR Gate
62. NOR Gate
A B Y
A B Logic(Y)
OFF
OFF
ON
ON
OFF
ON
OFF
ON
ON
ON
ON
OFF
A B Logic(Y)
OFF
OFF
ON
ON
OFF
ON
OFF
ON
ON
OFF
OFF
OFF
NAND Gate
B
Y
A
LADDER LOGIC FOR BASIC GATES…
70. The purpose of this system will be to indicate a “lit”
burner if at least two out of the three sensors indicate
flame.
If only one sensor indicates flame (or if no sensors
indicate flame), the system will declare the burner to be
un-lit.
The burner’s status will be visibly indicated by a lamp
that human operators can readily see inside the control
room area.
Examples of lit burner….
71. Each flame sensor outputs a DC voltage signal
indicating the detection of flame at the burner, either
on (24 volts DC) or off (0 volts DC).
These three discrete DC voltage signals are sensed by
the first three channels of the PLC’s discrete input card.
The indicator lamp is a 120 volt light bulb, and so must
be powered by an AC discrete output card, shown here
in the PLC’s last slot.
To make the ladder program more readable, we will
assign tag names (symbolic addresses) to each input
and output bit in the PLC, describing its real-world
device in an easily-interpreted format.
We will tag the first three discrete input channels as IN
sensor A, IN sensor B, and IN sensor C, and the output
as OUT burner lit.
Examples of lit burner….
72. Ladder logic of lit burner
“Burner is lit if either A and B, or either B and C, or
either A and C”
73. Logic gates of lit burner
Burner_lit = AB + BC + AC
Yet another way to represent this logical
relationship is to use logic gate symbols:
74. ADVANTAGES OF PLCS:
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.
75. Disadvantages of PLCs
PLC devices are proprietary it means that part or software of one
manufacturer can’t be used in combination with parts of another
manufacturer.
Limited design and cost option
Fixed Circuit Operations.
PLCs manufacturers offer only closed architectures.
76. APPLICATIONS:
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.
77. Basic parts of a PLC
Power Supply
Processor Module
CPU
Memory
Communication Interface.
HMI –Status
HMI –Programming
I/O Modules
Discrete/Digital Inputs
Analog Inputs
Output Modules
REVISION
78. ANALOG AND DIGITAL
The most basic element of automation logic is its digital
state.
A switch or signal may only be on or off.
This can be represented as a signal being a 0 (off) or a 1
(on).
There are many elements in an automation scheme that
can be represented as a 1 or 0—the state of a switch or
sensor; the state of a motor, valve, or pilot light; or even the
state of a machine itself.
The state of many devices cannot be so simply described.
79. A motor can be described as being on or off, but it has
other parameters, such as its speed, that can only be
described numerically.
For this purpose an analog representation of the value is
used.
Depending on the types of numbers that are used, an
analog value can be represented as an integer or a
fractional number with a decimal point.
ANALOG AND DIGITAL…
80. ANALOG AND DIGITAL…
Analog input signals take the form of changes in either
voltage or current.
The analog device may be measuring position, speed,
flow, or another physical characteristic.
These signals are connected to a circuit, which then
converts the signal into a digital number.
Output analog signals also take the form of changes in
voltage or current.
81. A digital set point is converted to an analog output,
which may drive the speed of a motor or the position of
a valve.
Analog inputs and outputs must go through these
digital-to analog and analog-to-digital conversions
because of the inherently digital nature of computer and
control systems.
ANALOG AND DIGITAL…
82. Electrical signals are converted to digital from analog inputs
using an analog-to-digital converter circuit (ADC).
Signals are converted from digital to analog using a DAC, or
digital-to-analog converter.
The number of digital steps that an ADC or DAC is capable of is
known as the resolution of the converter, this is described by the
number of bits of the digital signal.
A 16-bit DAC has a higher resolution than a 14-bit DAC, meaning
it displays a higher number of subdivided values within its range.
ANALOG AND DIGITAL…
83. INPUT AND OUTPUT (DATA)
The control of a system reacts to input information and
configures output(s) accordingly.
Input and output information can be in the form of physical
signals, such as electrical and pneumatic pulses or levels, or it
can be in a virtual form, such as text instructions or data.
A controller may react to switches or fluid levels by turning on
valves or running motors at a given speed, or a computer may
react to text or mouse-click-type instructions by changing
display screens or running a program.
These are both cause and effect illustrations of automation at
work.
84. DISCRETE I/O
Most control systems on a manufacturing plant floor
use discrete I/O (or input/output) in some form on
both the input and output sides of the process.
Digital signals, such as switches, push buttons, and
various types of sensors, are wired to the inputs of a
system.
Outputs can drive motors or valves by turning them
off and on.
85. ANALOG I/O
Analog inputs and outputs typically take the form of changes in
either voltage or current.
Analog inputs may represent the position of a device, an air
pressure, the weight of an object, or any other physical property
that can be represented numerically.
Most measurement systems use analog inputs.
Analog outputs may be used to control the speed of a motor, the
temperature of an oven, and many other properties.
87. PID CONTROL
Control of a closed-loop system is often done with PID
control algorithms or controllers.
A closed-loop system takes feedback from whatever
variable is being controlled, such as temperature or speed,
and uses it to attempt to maintain a set point.
PID stands for proportional-integral-derivative, the names
of the variables set in the controlling algorithm.
Another name for this is “three-term control.”
89. CONT…
In a closed-loop system, a sensor is used to
monitor the process variable of the system.
This may be the speed of a motor, the pressure
or flow of a liquid, the temperature of a process,
or any variable that needs to be controlled.
This value is then digitized into a numerical
value scaled to the engineering units of what is
being measured.
90. CONT..
The variable is then compared to the set
point for the system; the difference between
the set point and the process variable is the
error or difference that must be minimized
by the system.
This value is “feed back” into the system to
counteract the error
93. Communication Modules
Used to establish point-to-point connections
with other intelligent devices for the exchange
of data.
Such connections are normally established
with computers, operator stations, process
control systems, and other PLCs.
Communication modules allow the user to
connect the PLC to high-speed local networks
that may be different from the network
communication provided with the PLC.
94. COMMUNICATIONS
Communications methods can be applied to transfer larger
amounts of information to and from a controller.
With this method, digital and analog I/O statuses, along with
text and numerical data, can be transferred.
There are many different methods of communication based
input and output protocols
Many of the communication techniques described here have been
adapted to allow remotely mounted devices and I/O blocks to be
distributed to various locations on a machine or within a system
and to be controlled from a central point.
Devices and controllers are linked together to form a
communications network.
95. Many of the communication techniques described here
have been adapted to allow remotely mounted devices and
I/O blocks to be distributed to various locations on a
machine or within a system and to be controlled from a
central point.
Devices and controllers are linked together to form a
communications network.
A network may be as simple as two devices talking to one
another or a multilayered scheme with hundreds or even
millions of devices on it (as with the Internet).
Common topologies or layouts for networks include ring
or star configurations
An individual element of a network is also known as a
node.
97. SERIAL
Serial communications are strings of digital 1s and 0s sent over
a single wire.
They can alternate between sending and receiving data or have
a dedicated line for each signal.
The protocols for the data sent across the lines can vary widely
but a few of the common types of serial communications are
RS232, RS422 and RS485.
The RS in these designations is an acronym for “recommended
standard” and does not describe the actual communication
protocol being used.
RS232 communications typically use separate send and receive
lines.
These are labeled as TX for transmit and RX for receive.
98. SERIAL..
They can also use other lines such as CTS and CTR for
clear-to- send and clear-to-receive as a traffic control or
hardware handshaking method.
Serial ports also still exist in the Universal Serial Bus (USB)
world, not only through USB/serial converters, but also
because many USB devices use the USB port as a virtual
serial port.
100. USB…
USB is a configuration widely used in computer peripheral
devices, but it is beginning to be adopted into automation systems.
It was originally designed as a replacement for some of the RS232
and other serial connections on the backside of PCs.
Along with communications between peripheral devices, it can
also provide a limited amount of current to power devices.
USB signals are transmitted on twisted pair data cable.
Unlike some of the physical-only specifications described
previously, the USB standard also includes frame and
communications protocols for more commonality between
devices from different manufacturers.
101. PARALLEL
Parallel communications allow multiple bits to be transmitted
simultaneously over parallel lines.
This can increase the throughput of data over RS232 signals, but
it increases the cost of the cabling between two points.
A common use of parallel cabling is between a computer’s
parallel port and a printer.
Another common use of parallel communications is between
CPU chips and the various registers used for processing data on a
controller board.
This configuration is easily visible when looking at the many
parallel traces on a circuit board or the multicolored ribbon
cables that often connect boards to each other.
102. PARALLEL…
The backplanes of many control systems that connect
controllers to their I/O cards are often parallel busses.
Parallel communications are generally used over much
shorter distances than serial communications.
Female
Male
103. ETHERNET
Ethernet is a framework for computer networking technology that
describes the wiring and signaling characteristics used in local area
networks (LANs).
The medium used for cabling Ethernet communications can be in the
form of twisted pair wiring, coaxial cabling, or fiber-optic lines
between points.
As with the other communication methods described in this section,
Ethernet only describes the physical characteristics of the system in
terms of wiring and not the communication protocol used across the
wires or fibers.
104. ETHERNET…
Because of the widespread use of Ethernet in computing,
nearly every computer is now equipped with an Ethernet
port.
Switches and hubs are used to connect computers and
control devices in wide-ranging configurations.
There are two different pin configurations for standard
Ethernet cables: one with direct terminal-to-terminal
configurations used with switches and hubs, and another
known as a “crossover” cable for direct port-to-port
connection.
Ethernet communications are very fast in comparison to
serial and parallel communications and can transfer large
amounts of data quickly.
105. SPECIAL AUTOMATION PROTOCOLS
Many automation component vendors have
developed their own protocols for communications
using the various physical forms described above.
Communication of data between controllers and
operator interface touch screens are often developed
by the manufacturer and, as such, are not used
between different manufacturers.
To facilitate communication between different
manufacturers’ devices, drivers are made available to
allow devices to be easily interfaced.
106. Because of the interconnection problems between devices
from different manufacturers, protocols have been adopted
for communication and I/O control as standards.
Most of the following protocols are used for data
communication and distributed I/O between a main
controller and a remote node
DeviceNet is an open communications protocol used to
connect low-level devices, such as sensors and actuators, to
higher-level devices, such as PLCs.
Special Automation Protocols…
107. CANOpen is a communication protocol used in embedded
systems.
It is also a device profile specification that defines an
application layer for hardware. CAN Open consists of this
application layer, an addressing scheme, and several
smaller internal communication protocols.
Because it is a mature, open protocol, CANOpen is
supported extensively by servo and stepper controller
manufacturers.
Special Automation Protocols…
108. PROFIBUS is a bit-serial Fieldbus protocol developed by a
group of companies in Germany.
It is a global market leader among protocols because it
can be used in both production automation and process
automation.
PROFIBUS PA is a low-current variation used to monitor
measuring equipment in process automation (PA).
PROFIBUS DP (Decentralized Peripherals) is used to
operate sensors and actuators via a centralized controller
in a production environment.
Special Automation Protocols…
109. Fieldbus is a group of industrial computer
networking protocols developed for distributed
control in real time.
Prior to this development, computers were
often connected using RS232 or other serial
methods.
In general terms, a fieldbus can be described as
a network designed specifically for industrial
control.
Special Automation Protocols…
110. WIRELESS
Wireless network refers to any type of computer network
that is not connected by cables of any kind.
This method avoids the more costly process of routing
cables into a building or as a connection between distant
equipment locations.
Wireless telecommunications networks are generally
implemented and administered over radio waves.
This implementation takes place at the physical level or
layer of the network structure.
Examples are Bluetooth, Wi-Fi, Li-Fi etc.