Plc documentation final

Programmable Logic Control

Department of Electrical And Electronics

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TABLE OF CONTENTS
SL NO. CONTENTS

1.
2.
3.
4.
5.
6.
7.

Processor Information
Theory
About Allen Bradley PLC
Pin Diagram
Channel Configuration
Configuration of network through LAN
To glow a bulb using NO and NC switch.
Where NO switch starts the operation
and NC switch to close the operation.
8. To glow a bulb after few seconds delay.
9. Switching of bulb after 5 second and Fan after
10 second.
10. Use binary bit for switching the bulb after 5 second
and fan after 10 second.
11. Perform sequencing by switching on bulb after
4 second then fan 1 after 10 second and finally
fan 3 after 12 second.
12. Perform the sequence switching then OFF all
of them after 5 second when all devices are
switched ON.
13. Switch the bulb, fan 1 and fan 2 in sequence
and then stop fan 2 first then fan 1 and finally
the bulb.
14. Toggling of two LED’s.
15. Toggling of three LED’s
16. By the use of proximity sensor and the counter stop
the motor of conveyer belt when the sensor sense
metal pieces more than 5 times.


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03
03
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15

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25

27

30
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34

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PROCESSOR INFORMATION:

Programmable Logic Controller
PLCs were first introduced in the 1960’s. The primary reason for
designing such a device was eliminating the large cost involved in
replacing the complicated relay based machine control systems.
Bedford Associates (Bedford, MA) proposed something called a
Modular Digital Controller (MODICON) to a major US car
manufacturer. The MODICON 084 brought the world's first PLC into
commercial production.
A Programmable controller is a solid state user programmable
control system with functions to control logic, sequencing, timing,
arithmetic data manipulation and counting capabilities. It can be
viewed as an industrial computer that has a central processor unit,
memory, input output interface and a programming device. The
central processing unit provides the intelligence of the controller. It
accepts data, status information from various sensing devices like
limit switches, proximity switches, executes the user control
program stored in the memory and gives appropriate output
commands to devices such as solenoid valves, switches etc.


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Advantages PLC controller can be presented in few basic
points:
1. Compared to a conventional process control system, number of
wires needed for connections is reduced by approximately 80%
2. Diagnostic functions of a PLC controller allow for fast and easy
error detection.
3. Change in operating sequence or application of a PLC
controller to a different operating process can easily be
accomplished by replacing a program through a console or using
PC software (not requiring changes in wiring, unless addition of
some input or output device is required).
4. Needs fewer spare parts
5. It is much cheaper compared to a conventional system,
especially in cases where a large number of Input/Output
instruments are needed and when operational functions are
complex.
6. Reliability of a PLC is greater than that of an electro-mechanical
relay or a timer, because of less moving parts.
7. They are compact and occupy less space
8. Use of PLC results in appreciable savings in Hardware and wiring
cost.


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PLC Operation
A PLC works by continually scanning a program. We can think of
this scan cycle as consisting of 3 important steps. There are
typically more than 3 but we can focus on the important parts
and not worry about the others. Typically the others are checking
the system and updating the current internal counter and timer
values. The first type of scanning, as shown in the diagram below,
is not as common as the type that will be discussed second.

PLC Scan Diagram

The first step is to check the input status. This step is therefore
generally referred to as the “Check Input Status” stage. First the
PLC takes a look at each input to determine if it is on or off. In
other words, is the sensor connected to the first input on? How
about the second input? How about the third? This goes on and
on through the entire program.
It records this data into its memory to be used during the next step.
Next the PLC executes your program one instruction at a time,
called the “Execute Program” stage. For example, if your program
said that if the first input was on then it should turn on the first
output. Since it already knows which inputs are on/off from the
previous step it will be able to decide whether the first output
should be turned on based on the state of the first input. It will
store the execution results for use later during the next step.
Finally the PLC updates the status of the outputs. It updates the
outputs based on which inputs were on during the first step and
the results of executing your program during the second step.


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Based on the example in step 2 it would now turn on the first
output because the first input was on and your program said to
turn on the first output when this condition is true.
A new style of scanning has been implemented in the more
recent years, called “rung scanning”. This type basically scans
each ladder rung individually in the entire ladder logic program,
updating the outputs on that rung after scanning through the
inputs. This changes the type of programming that will be used as
well. If an output is in a rung above the inputs it depends on, you
will not get the output updated until the next scan, as the
program will keep scanning down until the last rung, then start
over. This style is very advantageous in certain situations. If you
want your outputs updated at the soonest possible moment, this is
the style of scanning that you want to use.

ACTUATORS
Actuators convert electrical signal from PLC into a physical
condition. Actuators are connected to the PLC output. A moter
starter is one example of an actuator that is connected to the PLC
output. Depending on the output PLC signal the motor starter will
either start or stop the motor.


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SWITCHES:

In PLC we use the limit switches which are given

below:

Limit switch


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Ladder Logic
Ladder logic is one form of drawing electrical logic schematics,
and is a graphical language very popular for programming
Programmable Logic Controllers. Ladder logic was originally
invented to describe logic made from relays. The name is based
on the observation that programs in this language resemble
ladders, with two vertical "rails" and a series of horizontal "rungs"
between them. Figure 5 below is a very basic example of ladder
logic used in a programmable logic controls program.

Basic Ladder Logic Program

Ladder Logic Programming
Ladder logic or ladder diagrams are the most common
programming language used to program a PLC. Ladder logic was
one of the first programming approaches used in PLCs because it
borrowed heavily from the relay diagrams that plant electricians
already knew. The symbols used in relay ladder logic consist of a
power rail to the left, a second power rail to the right, and
individual circuits that connect the left power rail to the right. The

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logic of each circuit (or rung) is solved from left to right. A
common mistake made by most people is trying to think of the
diagram as having to have current across the rung for the output
to function. This has given many people trouble because of the
fact that some inputs are “not” inputs, which will be true when
there isn’t current through this sensor. These concepts will be
discussed more latter. The symbols of these diagrams look like a
ladder - with two side rails and circuits that resemble rungs on a
ladder.

Simplified Logic Circuit
The logic of the rung above is such:
 If Input1 is ON (or true) - power (logic) completes the circuit
from the left rail to the right rail - and Output1 turns ON (or
true).
 If Input1 is OFF (or false) - then the circuit is not completed
and logic does not flow to the right - and Output 1 is OFF (or
false).
There are many logic symbols available in Ladder Logic - including
timers, counters, math, and data moves such that any logical
condition or control loop can be represented in ladder logic. With
just a handful of basic symbols such as a normally open contact,
normally closed contact, normally open coil, normally closed coil,
timer and counter most logical conditions can be represented.


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What is Allen Bradley PLC?
Allen-Bradley products from Rockwell Automation include
integrated control and information platforms, intelligent motor
control and industrial components. The Allen-Bradley
MicroLogix1400 from Rockwell Automation complements the
existing MicroLogix family of small programmable logic controllers.
MicroLogix 1400 combines the features you demand from
MicroLogix 1100, such as EtherNet/IP, online editing, and a built-in
LCD, plus provides you with enhanced features, such as: higher
I/O count, faster High Speed Counter/PTO and enhanced network
capabilities.


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Port Pin Diagram:


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Channel Configuration:


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Configuration of Network through LAN
Steps:
1. Open network & sharing centre through control panel.
2. Click on change adapter setting. A new window will open

3. Double click on local area connection. A pop-up menu will appear.

4. Select internet protocol version 4


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5. Configure the setting as follows & click ok.
6. Then select RS LINX classic from the start menu.a window will open then select
the EHERNET/IP driver from the drop down menu & click add new.

7. A new screen will appear. Select realtck pcie fe family controller & click ok.

8. The configuration has been now done & the system is ready for interfacing.


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Program 1:
To glow a bulb using NO and NC switch. Where NO switch starts the operation and
NC switch is close the operation.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize

Program File:


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PROGRAM DESCRIPTION:
The circuit consists of NO and NC switch, the output is latched with the NO. A bulb is
connected at the port 9 of the PLC. When the NO switch due to the latching the
bulb will continuously glow and pressing the NC the circuit is closed.

RESULT:
The bulb is glow NO and NC switch, where NO switch starts the operation and NC
switch is close the operation.

CONCLUSION:
Latching has been successfully done to glow the bulb continuously.


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Program 2:
To glow a bulb after few seconds delay.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Timer
5. Binary

PROGRAM DESCRIPTION:
In this circuit the NO and NC switch is used the output is latched by the internal bit.
Internal bit is a type of resistor because it is easy to use a bit to represent voltage
levels within the PLC. In this circuit we have use the 3’rd bit. The 3’rd bit is use to
activate the timer TON. Timer has pre-set of 10 second, after 10 second the by the
activation of DN (Done Bit) the bulb will start to glow.

RESULT:
The bulb starts to glow after a delay of 10 second by the use of timer.

CONCLUSION:
By the use of timer the bulb glows after a delay.


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Program File:


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Program 3:
Switch light after 5 second and Fan after 10 second.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Timer

Program File Description:
The circuit consists of NO and NC switch, the NO switch is latched with the timer
Enable Bit (EB). The timer T4:0 and T4:1 is connected in parallel the done bit of the
timer T4:0 is connected with the bulb and done bit of timer T4:1 is connected with
the fan. The timer T4:0 gives the delay of 5 second to start the bulb and timer T4:1
gives the delay of 10 second after the start to start the fan.

RESULT:
The light is switched after 5 second and fan start after 10 second.

CONCLUSION:
By connecting the timers in parallel we get the delay of 5 second for glowing bulb
and 10 second for the start of motor fan at the instant when we start the circuit.


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Program File:


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Program 4:
Use binary bit for switching the light after 5 second and fan after 10 second.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Timer
5. Binary

Program Description:
This program works similarly as the previous program, the only change made in this
program is that we activate the timer by the use of internal bit. The internal bit 3 is
use to activate both the timers and done bit T4:0/DN glow the bulb and T4:1/DN
starts the motor.

RESULT:
Binary bit is used for switching the light after 5 second and fan after 10 second.

CONCLUSION:
By using the internal bit B3 the timer is activated and we get the desired result.


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Program File:


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Program 5:
Perform sequencing by switching on bulb after 4 second then fan 1 after 10 second
and finally fan 3 after 12 second.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Timer
5. Binary

The circuit consists of NO and NC switch the NO is latched with the internal bit B3:1.
This bit is use to activate the timer T1which is having the pre-set value 4 second. The
DN bit of the timer ON the bulb after 4 second.


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Program File:


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Program 6:
Perform the sequence switching then OFF all of them after 5 second when all
devices are switched ON.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Timer
5. Binary

The NO switch is latched with the internal bit B3:0/3, this bit is use to activate the
timer T4:0. The DB of the timer is use to active the internal bit B3:0/4 and this bit is use
to glow the bulb after 4 second which is at the output port 3. The bit B3:0/4 is use to
activate the timer T4:1, the DN bit of the timer is use to activate the bit B3:0/5 and
this bit is use to run the motor of fan after 10 second after the starting of the circuit.
The binary bit B3:50/5 is use to activate the timer T4:2 and DN bit of this timer is use of
run the fan 2.

RESULT:
The sequence switching has been performed and then we OFF all of them after 5
second when all devices are switched ON.


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Program File:


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Program 7:
Switch the bulb, fan 1 and fan 2 in sequence and then stop fan 2 first then fan 1 and
finally the bulb.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Timer
5. Binary

In rung 0 the internal bit is latched with the internal bit 1, this bit is use to
activate the timer T4:0. The DN bit of the timer is initiating an internal bit 15,
this bit along with the DN bit of timer T4:3 in NC mode are connected with the
bulb. Similar process is done for both the fan1 and fan2 with different bits and
timers. In rung 8 the internal bit 13 is initiating the timers 4, 5 and 6. With the
help of these timers the circuit is sequentially stopping.
RESULT:
The circuit is first ON sequentially then fan2 stops first, then fan1 and finally the bulb.

CONCLUSION:
In stopping all the devices in sequence we have used three more timers so that with
their delay times the circuit stops sequentially.


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Program File:


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Program 8:
Toggling of two LED’s.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Timer
5. Reset

The circuit is initially having the NC switch which is the DN bit of the timer 2 i.e T4:1
connected with the timer T4:0. The DN bit of the timer glow the LED at the output
port 6. The NC switch which is the DN bit of timer 1 i.e T4:0 which is connected with
LED at port 7. The DN bit of the timer 1 which is the NO switch connected with the
timer 2.

RESULT:
By the given circuit diagram the two LED’s are toggled.

CONCLUSION:
The LED at the port 6starts glowing and after 2 second the LED at port 7 glow. The
toggling time is 2 second.

Program File:


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Program 9:
Toggling of three LED’s.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Timer
5. Reset

The circuit consists of three timers T1, T2, T3. DN bit of the timer 1 is connected with
the timer 2 and DN bit of timer 2 is connected with timer 3. In rung 4 the DN bit of the
timer 1 is in NO fashion and timer 2, timer 3 is in NC fashion. Initially when timer 1 is
starts after 2 second LED at port 6 glow keeping LED at output port 7 and 8 off. In
rung 5 DN of timer 2 is in NO fashion and timer 1, timer 3 is in NC fashion which will
glow LED 7 keeping LED 6 and 8 off again in rung 6 DN of timer 3 is in NO which will
glow LED 8 keeping LED 6 and 7 closed. Finally for continuously toggling all the timer
has to be reset thus taking the enable bit of all the timers in the form of NO switch we
will reset all the three timers connecting all the three in parallel.

RESULT:
The toggling of three LED’s has been performed successfully.

CONCUSION:
In toggling the three timers must be reset continuously and when one LED is glowing
the other two must be close.


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Program File:


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Program 10:
By the use of proximity sensor and the counter stop the motor of conveyer belt when
the sensor sense metal pieces more than 10 times.

Components Used:
1. Examine if Open
2. Examine if Close
3. Output Energize
4. Counter

For this program statement we have to use the up counter, the counter starts
counting when the metal is detected. When the counting reaches 10 the DN bit of
the counter enable an internal bit B3:0/1 this bit stops the motor at the output 4 by
the use of NC switch which gets open when the internal bit B3:0/1 is active. To stop
the counter i.e to turn off the operation the NC i.e I:0/0 which acts a Switch Off
switch as placed in the rung 0.

RESULT:
By the use of proximity sensor and the counter we stop the motor of conveyer belt
when the sensor sense metal pieces more than 10 times.

CONCLUSION:
The sensor starts detecting the metal after counter counts till 10 the motor stops. The
input switch which is at port 0 will stop the operation when counts reach the set
value.


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Program File:


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