Date of Experiment: 12/5/2016

Report due date:17/6/2016

Report submission date: 17/6/2016

Checked by:

Item/marks

Format/10

Abstract and Introduction/10

Figures and Diagrams/15

Materials and Method/10

Results Discussions/45

References/10

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PROGRAMMABLE LOGIC CONTROLLER (PLC)

(Short Report / Long Report)

Student Name

Wong Shin Chien (0317415)

Group Members

Jane Lee Song Ern

Yap Yi Wei

School of Engineering

Taylor’s University

Malaysia

12 May 2016

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Table of Contents

Abstract 3

1.0 Introduction 4

2.0 Experimental Design 6

2.1 Materials and Apparatus 6

2.2 Methodology6

2.3 Experimental Procedure 7

3.0 Results and Discussion 10

4.0 Error Analysis 20

5.0 Conclusion 21

Reference 22

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Abstract

This report consist of 4 discussion from 4 different experiment done on the same

machine which is the PLC OMRON SYSMAC CS1G-CPU42H (Programmable

Controller) by using CX programmer as the executing tool for the program that

students wrote. The PLC trainer is tested with inputs such as simple PB start switch,

Timer switch, sensors switch, and relay switch. The first experiment allow us to

understand that the circuit will still continue to flow when the relay switch is turned

on even after the PB start switch is deactivated again. Experiment 2 allow students to

understand that there is a delay for the circuit to flow through parallel circuit when the

parallel timer switch is switched on after certain amount of time that is set by students

usually in seconds. 3rd Experiment shows the combination of components such as

relay switch and timer switch. The relay switch is off when the main path of the

circuit which is controlled by the timer switch is open after the timer ends. It shuts

down the only path that completes the circuit therefore the lamp is off after the timer

ends. Experiment 4 is a more sophisticated experiment which includes transformation

of electrical signals into mechanical movement with controlled time and direction of

movement of the car. The sensors switches on and off after the car passing through

the sensor which will activate the related switch and the car changes direction. The

experiment is done successfully with the steps carefully followed by students

according to the lab sheet.

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1.0 Introduction

Programmable Logic Controller (PLC) is a device that take inputs from user and gives

desired output which is programmed by the user. PLC can perform task such as receiving

signal generated by sensors which is stimulated by physical stimuli.

A programmable logic controller (PLC) is used for automation process in industry such as

assembly lines, temperature control, lighting control etc[1]. PLC are designed for multiple

input and outputs. It should withstand harsh environment which can function under extended

temperature ranges, resistance to vibration and impact, etc[2].

Early PLCs were designed to replace relay logic systems[3].Ladder logicis the programming

language for PLC which looks like a diagram of relay logic. This is to reduce the difficulties

for existing technicians.

Modern PLCs can be programmed in a variety of ways such as specially adapted dialects

of BASIC and C[4]. They also used state logic which is a very complex and high level

programming language specially designed to program PLCs.

PLC is a computer, it has a CPU which carry out function such as:

Store user commands in a non-volatile memory which will not be erased even there is

an electrical breakdown.

Communicate with other devices such as sensors, actuators etc.

Perform house-keeping activities including communications, internal diagnostics and

etc.

A basic PLC system follows 4 steps of operation which is stated in the table below:

Table1: Operational Steps and its functions

Process FunctionsInput Scan Detects the state of input devices

Program Scan Executes logic created by user

Output Scan Energize/de-energize state of output devices

House-Keeping Internal diagnostics, communications, programming

terminals, etc

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For our experiment, the programming software that we are using is CX programmer to

execute our commands and programming diagram on the PLC.

Figure 1.2 CX programmer software [5]

It creates advanced programs using data blocks of identical data types (Arrays), or different

data types (Structures. It also create symbols quicker as it has automatic memory allocation

and management. Students then easily monitors the state of the input and output devices in

the computer to check whether the output produced is correct. TIMER (count-down) and

COUNTER (count-up) symbols allows easy track of timer and access the value and students

can modify it by accessing it according to their specific names such as TIM 0001. That means

zero maintenance to resolve addresses when a program is very complex and just a single data

is needed to be modified.

2.0 Experimental Design

5

Figure 2.1: OMRON Programmable Logic Controller (PLC)

2.1 Materials and Apparatus

1. OMRON SYSMAC CS1G-CPU42H (Programmable Controller)

2. CX- Programmer

3. Computer

2.2 Methodology

For every experiment, students are required to draw the input and output devices in the CX

program based on the lab sheet provided. The next step is to set value and names for the

devices drawn in the CX program. After troubleshooting and confirmed that the circuit is

functioning, it is sent to the PLC OMRON SYSMAC CS1G-CPU42H and executed. The

switch on the PLC is switched on and off depending on the experiment procedure. The result

for each action taken is recorded and screenshotted for report writing purposes.

2.3 Experimental Procedure

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Experiment 1

Figure4:Conventional Circuit for Experiment 1

1. An input and output table together with a ladder logic diagram was drawn as shown

respectively for the conventional circuit as shown in Figure4 above.

2. Ladder logic diagram was developed in the CX programmer and transferred to the

PLC.

3. Program was run and executed and hence observations and explanations were made.

Experiment 2

Figure5: Conventional Circuit for Experiment 2

1. An input output table together with a ladder logic diagram was drawn as shown in

Figure 5.

2. The timer was set to 5 seconds.

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3. The ladder logic diagram was developed in the CX-Programmer and the program was

transferred to the PLC trainer.

4. The program was run and executed and hence observations and explanations were

made about the application.

Experiment 3

Figure6: Conventional Circuit for Experiment 3

1. An input output table together with a ladder logic diagram was drawn as shown in

Figure 6.

2. The timer was set to 8 seconds.

3. The ladder logic diagram was developed in the CX-Programmer and the program was

transferred to the PLC trainer.

4. The program was run and executed and hence observations and explanations were

made about the application.

Experiment 4

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Figure7: Conventional Circuit for Experiment 4

1. An input and output table together with a ladder logic diagram was drawn as shown for

the conventional circuit as shown in Figure7 above.

2. Timer was set to 5 seconds.

3. Ladder logic diagram was developed in the CX programmer and transferred to the PLC.

4. Program was run and executed and hence observations and explanations were made.

3.0 Results and Discussion

9

Experiment 1

Table 3.1: Input output table for experiment 1

INPUT DEVICE COMMAND OUTPUT DEVICE COMMAND

PB Start 0.01 Relay Coil 1.01

PB Stop 0.02 Lamp 1 1.02

Figure 3.2: Ladder logic diagram Experiment 1

PB Start button is Normally Open, which means when the button at the PLC trainer is

activated, the circuit will be complete and allow current to flow through it.

PB Stop button is Normally Closed, which means when the button is activated, the

circuit will be cut and stop the current to flow through it.

Relay Coil will be activated when there is a current flowing through it. The parallel

circuit of relay coil will support the current flow even the PB Start is switched off

later after it is being activated.

Lamp will be activated when there is current flowing through it.

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Figure 3.3: Circuit of PB start activated and PB stop deactivated.

It is clear that when current is allowed to flow and PB start is activated and pass through PB

Stop which is normally closed and it activates the relay coil and parallel current flow through

it and activates the lamp.

Figure 3.4: Circuit of PB start deactivated and PB stop deactivated.

Even that when the PB Start is deactivated again, the parallel relay coil has already been

activated and supports the current flow through PB Stop and continue relaying itself and

activates the lamp.

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Figure 3.5: Circuit of PB Stop activated.

The circuit path for the current to flow has been cut. There is no way for the relay to continue

function as the activator for the relay cannot be reach by current. This causes the circuit to be

incomplete and the lamp is deactivated.

Figure 3.6: Circuit of PB Start activated and PB Stop activated

Even PB start is activated, there is no way to activate the relay coil and lamp as PB Stop is

the only path that allow the circuit to be completed. Nothing will be activated if PB stop is

activated.

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Experiment 2

Table 3.7 Input and Output table Experiment 2

INPUT DEVICE COMMAND OUTPUT DEVICE COMMAND

Latching Switch 0.01 Timer 1 TIM 1 #0050

- - Lamp 1 1.01

Figure 3.8: Ladder Logic Diagram for Experiment 2

Switch 0.01 is a Normally Open switch. It will allow current to pass through if it is

activated.

Timer switch is coded as TIM 0001 and preset a timer of 50 milliseconds. It will

count for 50 milliseconds before it turns on the circuit and allow the circuit to be

closed for T0001 switch.

Lamp will be activated if current flows through it.

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Figure 3.9: Switch 0.01 is activated

When the normally open switch 0.01 is activated, the currents flows through the timer switch

which starts to count for 50 milliseconds. Note that the circuit is not complete when it haven’t

finished counting.

Figure 3.10: Complete circuit after timer switch finishes counting

After counting for 50 milliseconds, the normally open timer switch is now closed. Current

flows through the circuit and completes it while activating the output, which is the lamp.

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Experiment 3

Table 3.11 Input and Output Table For Experiment 3

INPUT DEVICE COMMAND OUTPUT DEVICE COMMAND

PB Start 0.01 Relay Coil 1.01

- - Timer 1 TIM 1 #0080

- - Lamp 1.02

Figure 3.12: Ladder Logic Diagram Experiment 3

Switch 0.01 which is normally open

Timer contact is Normally Closed this time. Means after the counting of the timer the

circuit will open and stops the current flow

Relay switch allow parallel current flow through the relay coil when current is

supplied to the switch.

Lamp activates when current flows through it.

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Figure 3.13 PB start activated

When PB Start is activated, it activates the relay coil and timer contact. Parallel current flows

through the relay switch which is now closed. The lamp is activated as current flows through

parallel circuits.

Figure 3.14 PB start deactivated

When PB start is closed, current is still flowing through the relay, timer switch, and lamp

because the relay coil is still supplied with current. The timer switch is still counting for 80

milliseconds.

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Figure 3.15: Timer switch finishes counting

When timer switch finished counting for 80 milliseconds, the timer contact switch is now

open as it is Normally Closed before. This shuts down the current that flow through it. Now,

the relay coil is not supplied with current, therefore, the relay switch is now open again. The

lamp does not receive current and therefore is not activated.

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Experiment 4

Figure 3.16 When LS1 and PB start is activated

When LS1 and PB Start are activated, it passes through PB Stop and LS2 which are Normally

Closed and activates Motor Right switch which is normally opened. The car will move to the

right. Even when the PB start is deactivated now, the motor will still be moving right.

Figure 3.17 When LS2 activated

When the motor reaches the end, LS2 sensor sense the car and open the Normally Closed

LS2 switch which stops the Motor Right from moving. It also activates the Timer switch

which counts for 50 milliseconds.

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Figure 3.18 When Timer switch finishes counting and motor Left activated

After counting for 50 milliseconds, timer switch is closed and LS1 switch which is normally

closed allow currents to flow through and activates Motor Left. The car moves left. And after

the car reaches the Left end, LS1 sensor will sense the car and open the Normally Closed LS1

switch which cuts off the current and motor left stops. The car is back to original position.

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4.0 Error Analysis

For experiment 1, Relay coil is the risk that will cause error to the PLC system. This is due to

the electromagnetic force generated is not strong enough to allow the switch to contact with

it. Causing no current to flow through it after PB Start is switched off.

For experiment 2, malfunction of timer switch will cause the timer to be looping forever

without activating its timer switch. This will shut down the current that should be passing

through the lamp.

For experiment 3, risk and error caused will be similar to experiment 1 and experiment 2 as

the components used in experiment 3 consists of components that being used previously such

as relay and timer switch.

For experiment 4, the sensor will probably causes error as student might accidentally put their

hands along the path of the sensor which sends a signal to the PLC to stops the motor before

it is supposed to be stopped. This will greatly affect the outcome of the result that students

wanted to obtain.

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5.0 Conclusion

After completing the experiment, students are able to understand the functions of the

components that is used to draw the ladder logic using CX programmer software. A relay coil

will allow current to flow through the switch when the current is supplied to it. A timer

switch will allow switches to turn on and off based on the delay time set by the user. Sensors

instantly changes the related switch when it is blocked by an object such as the car that

blocking its sensing path.

For experiment 1, the key learning is to understand that the circuit will continue to flow when

the relay coil is supplied with current. Even after the PB start is deactivated, the parallel

circuit still loaded with current will continue to supply current to the lamp. It can only be

turned off by activating the PB stop button which is Normally Closed because it is located at

the only path the current move across. This will shut down the relay coil and shutdown the

lamp.

For experiment 2, key learning is to manipulated variable such as time. A delay can be set by

students to demand a presence of current after certain amount of time. When the timer

finishes counting, the current starts flowing through the parallel current path and supply

energy to the lamp.

For experiment 3, key learning is to combine several components to produce a new and more

complex function based on experiment 1 and 2. This helps students to design complex system

that not just uses one components but more than one components to produce complex

function.

Experiment 4 teaches students to convert electrical signals into mechanical movement by

adding actuators such as electric motors in this experiment. The car is actuated to move left

and right when the motors is activated by sensors when the car move pass through it,

blocking its receiver. The setting is a good practice and students can draw a more complex

ladder logic that move in a more complex direction.

Lastly, the experiments carried out had help students understand more about PLC and help

student to prepare for the industrial environment when they starts to work in industry where

PLC is often used by companies in assembly lines. It is very beneficial to have knowledge on

PLC to alter the assembly plan to produce more value to the company by modifying the robot

movement for better production cycle time.

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References

[1] E. A. Parr, Industrial Control Handbook, Industrial Press Inc., 1999 ISBN 0-

8311-3085-7

[2]  M. A. Laughton, D. J. Warne (ed), Electrical Engineer's Reference book, 16th

edition,Newnes, 2003 Chapter 16 Programmable Controller

[3] "The father of invention: Dick Morley looks back on the 40th anniversary of the

PLC". Manufacturing Automation. 12 September 2008.

[4] Harms, Toni M. &Kinner, Russell H. P.E., Enhancing PLC Performance with

Vision Systems. 18th Annual ESD/HMI International Programmable Controllers

Conference Proceedings, 1989, p. 387-399.`

[5] CX Programmer 9.1, undated, Omron , [online], Viewed: 14/6/2016, Available at:

https://industrial.omron.eu/en/products/cx-programmer

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