International Journal of Electronics and Computer Science Engineering
Available Online at www.ijecse.org
91
ISSN- 2277-1956
Implementation of PLC Based Elevator Control
System
Sandar Htay 1, Su Su Yi Mon
12
2
Department of Electronics Engineering, Mandalay Technological University(MTU), Myanmar
Abstract-This paper describes programmable logic controller based elevator control system. An elevator is
one of the important aspects in electronics control module in automotive application. Nowadays, Myanmar is
a developing country and there is enormous increase in high-rise building in Myanmar. This paper mainly
focuses on using programmable logic controller to control the circuit and building the elevator model. Hall
Effect sensor is used for the elevator position. DC Motor is used to control the up and down movement of the
elevator car. Push buttons are used to call the elevator car. The elevator position is described by using the
display unit. In this paper, Auto Station Software ladder logic program is used for four floors control system.
Keywords –WPLC, Elevator Design, Hall Effect sensor, DC motor, Ladder logic
I. INTRODUCTION
For most people residing in urban cities, elevators have become an integral part of their daily life. Simply stated,
an elevator is a hoisting or lowering mechanism, designed to carry passengers or freight, and is equipped with a car
and platform that typically moves in fixed guides and serves two or more landings.
Hydraulic and roped elevators are the two types of elevators in use today. The main design considerations for
choosing either electric traction drive or hydraulic for a particular project are the number of floors, the height of the
building, the number of people to be transported, desired passenger waiting times and frequency of use.
This project is to design and construct an elevator using a programmable logic controller. Hall Effect sensor is
used to know the elevator position. Hydraulic and roped elevators are the two types of elevators in use today.
Elevators are prevalent throughout many multi-level structures.
II. RELATED WORK
In [9], the author explained that an approximate small-scale elevator model with PLC is adopted for the
controller design which uses the Ladder Language based on the GE FANUC VersamaxPLC.The ladder logic has
implemented by using VersaPro. 2.02.In this control design technique, the Light Dependent Resistor (LDR) is used
to sense the elevator floor.GE FANUC Versamax PLC is having a configurable memory of 64kbyte. The author
provided to improve the quality in elevator systems, develop and drives the used setting and increase the reliability
of elevator. The author also mentioned to achieve high speed nine-phase Permanent Magnet Synchronous Motor
Control System.
In [10], the author mentioned that making of wireless module to realize the transmission of user information,
PLC control system are adopted, the serial communication mode between the PLC and the wireless module was
adopted.SI4432 Transceiver, Single-Chip computer and PLC are used to modify the control system of construction
elevator.The control system of the construction elevator was made up of PLC, wireless calling device and wireless
host transceiver. Elevator control system can determine the next travel direction based on the call information and
the current operation automatically, realizes unattended operation.
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IJECSE, Volume3, Number 2
Sandar Htay and Su Su Yi Mon
In [11], the author described the application of sate chart to the modeling, design and implementation of an
elevator system, whose system behavior involves aggregating complexity of state descriptions, and imposition of
underlying control policy. Based on the operational flow of an elevator, they derive the associated state chart model
by looking into the inherent hierarchical structure of the elevator. This research was supported in part by the grant
NSC90-2213-E-011-020 and NSC90-2212-E-014-023 by the National Science Council, Taiwan, R.O.C.
III.PROGRAMMABLE LOGIC CONTROLLER
The first Programmable Logic Controller, PLC was developed by a group of engineers at General Motors in
1968. It was developed when that company was looking for an alternative to replace complex relay control system.
The term ‘programmable logic controller’ is defined by EN 61131-1 as a digitally operating electronic system which
uses a programmable memory for the internal storage of user-oriented instructions for implementing specific
functions such as logic, sequencing, timing, counting and arithmetic to control through digital or analogue inputs
and outputs, various machines or process.
A. Ladder Programming algorithm –
There are many types of programming languages in Programmable Logic Controller, PLC. Languages are
typically fixed to Ladder Logic (LD), Sequential Function Block (SFC), Function Block Diagram (FBD) and
Structure Text (ST). The common program language of PLC is ladder diagram.
B. Ladder Logic
Ladder diagram is an automatic control diagram language that developed during World War II. Ladder logic is the
primary programming language of programmable logic controllers. Since the PLC was developed to replace relay
logic control systems, it was only natural that the initial language closely resembles thediagrams used to document the
relay logic. By using this approach, the engineers and technicians using the early PLCs did not need retraining to
understand the program. To introduce ladder logic programming simple switch circuits are converted to relay logic
and then to PLC ladder logic. Any control task modifications are done by changing the program. This is why the use
of the PLC is preferred to the traditional hard wired circuits in industrial controls.
Figure 1. PLC Architecture
Figure 2. Ladder diagram althogorithm
In the chart of traditional ladder diagram, if X0, X1, X4 and X6 are in ON condition and the others are in OFF
condition, output point Y0 will be in ON condition as shown as dotted line in the figure 2.
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Implementation of PLC Based Elevator Control System
C. Ladder Softwre Pakage
The AutoStation installation package issued by Invt Auto-Control Technology is an executableprogram.The
main interfaces include 7 sections: Menu, Tool bar, Project Manager Window, Instruction Tree window,
Information window, Status bar and Operation area.
Figure 3. Auto Station main interface
IV. PROPOSED SYSTEM
In order to design a control circuit, it is divided into several units or modules for its particular task or control
which first can be tested or implemented independently and then combined together. The basis of PLC based
elevator control can be classified into three main groups. The first is the floor, the second is the PLC controller and
the last is the Elevator. The block diagram of PLC Based Elevator Control System is described in Figure 4To
accomplish the PLC based control system, the design uses six major components: PLC controller, DC motor driver,
push button, level sensor, display unit and Elevator. Level sensors are used to know the elevator position and push
buttons are used to be input by the user request. The display unit will display the number of floor. The PLC
compares the user request and the push button to drive the elevator motor Up or Down. When the user request is
greater than the sensor value, the motor will go up and it is less than the sensor value, it will go down. When the two
values are equal, the motor must stop.
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IJECSE, Volume3, Number 2
Sandar Htay and Su Su Yi Mon
Figure 4. Block diagram of PLC based elevator control system
This design can be divided into several units or modules. They are sensor unit, processing unit and power unit.
There are some devices and components used in the in the design to implement each unit. These devices used in this
system are as follows;
Power Supply Unit
Hall Effect sensor
IVC1 1410MAT PLC controller
H-bridge DC motor
Push Button
Display Unit
Elevator
A. Power Supply Unit
The DC power supply unit is vital component in modern electronic devices as they need a wide range of DC
voltages for their operations. The purpose of a power supply is to provide the required amount of power specified
voltage from primary source.
B. Description of Hall Effect Sensor
A Hall Effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall Effect
sensors are used for proximity, positioning, speed detection and current sensing applications.In its simplest form, the
sensor operates as an analogue transducer, directly returning a voltage. A Hall Effect sensor can be used to measure
the current without interrupting the circuit. Frequently, it is combined with circuitry that allows the device to act in a
digital (on/off) mode and may be called a switch. It is commonly used to time the speed of wheels and shafts, such
as for internal combustion engine ignition timing, tachometers and anti-lock braking systems. It consists basically of
a thin piece of rectangular p-type semiconductor materials. A typical Hall Effect sensor has three wires or terminals;
one for ground, one for supply or reference voltage and one for output. To produce an output signal, it must be
supplied with a voltage from 5 to 12 V. There are many different types of magnet movements, such as Head-on,
Sideways, Push-pull, and Push-push detections.
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(a)
(b)
Figure 5. (a) Heard-on detection (b) How Hall Effect works
C. Features of IVC1 1410MA TPLC Controller
The programmable controller PLC that is used in this research is IVC1-1410MAT.
IVC1 1410MAT. It has 14 inputs and 10 outputs.
As shown in Figure 6,, PORT0 and PORT1 are for communication. PORT0 is RS232, and use socket Mini DIN8,
while PORT1 is RS485 or RS232. The bus socket is for connecting extension modules. The mode selector switch
can be set to ON or OFF.
Figure 6. Structure of IVC1 series basic module
D. H-bridge DC Motor
Bidirectional control of a DC motor requires a circuit called an H-bridge.
H
The H-bridge,
bridge, named for its schematic
appearance, is able to move current in either direction through the motor winding. H-bridge
bridge topology was chosen in
this system. An H-Bridge
Bridge configuration using BJTs is shown in Fig 3.11. It is called an “H-Bridge”,
“H
because it looks
like an H letter. An H-bridge
bridge is an electronic circuit which enables electric motors to be run forward or backward
b
action. It is mostly used in motor control of elevator. It is available as integrated circuits or can be built from
separate components for specific design. In this system, the DC motor with H-bridge
H bridge driver circuit is used to
advance the elevator car
ar to the next position. The motor can provide for both directions: clockwise (CW) direction
and counterclockwise (CCW) direction. This circuit uses four transistors for forward and reverse directions. Its
operation is as follows. To rotate the DC motor ffour
our transistors are used. When the transistor Q1 and Q4 are ON
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IJECSE, Volume3, Number 2
Sandar Htay and Su Su Yi Mon
and the other transistors are OFF, a positive voltage will be applied across the motor and the motor will rotate
clockwise direction. When the transistor Q2 and Q3 are ON and the other transistors are OFF, the voltage across the
motor will be negative, allowing counterclockwise operation of the motor. In DC motor, clockwise direction for Upcondition and counter clockwise direction is for Down-condition.
Vcc
A
Q1
D
Q3
M
B
Q2
Q4
C
GND
Figure 7. H-bridge DC-motor Circuit
The motor used here is a H-bridge DC motor. Base on the design specification the output power and the output
torque of the motor are calculated by a simple calculation. The power and torque calculation are mentioned as
follow.
Weight of empty cabin = 100 kg
Counter weight = 100 kg
8persons with 65kg = 520 kg
For constant speed operation of 1m/s = 60m/1min
The power, work and force and torque are calculated using the equations (1 ), ( 2 ), (3 ), (4) and (5 ).
Power = work / time
(1)
Work = Force x distance
(2)
Force, F = mg
(3)
Power = Force x distance / time
So, Power = Force x velocity
(4)
F = 520 x 9.8 = 5096 N
P = 5096 x 1m/s = 5096 W
1hp = 745 W
5096 W = 6.84 hp (approximately 7hp or 5215W)
Rotational Speed ߱= 1500rpm
The torque of the motor can be calculated by using the equation(5)
Torque of motor (Nm) = Power in Watts
(5)
2πω
=
5125
2π × 1500
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=
5125
9424.778
= 0.54Nm
V. SIMULATION RESULTS
The simulation of elevator position control is carried out with the Auto Station in order to know theperformance of
the controller.AutoStationsoftware platform is use to perform the experiment. The PLC for experiment is equipped
withIVC1-1410MAT programmable logic controller.
In this system, theladder program must be run in the PLC controllerby downloading ladder softwre.
Basic requirements are also needed;
PLC
Programming Device ( personal computer )
Connector Cable
Programming Software
A. Specification of PLC controller
IVC1 1410MAT programmable logic controller with Auto Station software has been chosen for developing and
ladder logic was downloaded into the PLC. For the working model of an elevator various logics for different
operations have to be developed and it is discussed in the following.
Table -1 SPECIFICATIONS OF IVC1 1410MAT DEVICE
Digital I/O points
Total number of
supported I/O
points
Max. number of
special modules
High speed pulse
output
Single phase
counting channel
Max. total
frequency of highspeed counter
User program
Timer
Counter
Power supply
14-input /10-output
24
4
2×100kHz (for transistor output only)
6: 2(50kHz) + 4 (10kHz)
60kHz
24kByte
100ms precision: T0 ~ T209
10ms precision: T210 ~ T251
1ms precision: T252 ~ T255
16-bit up counter: C0 ~ C199
32-bit bi-directional counter: C200 ~ C235
32-bit high speed counter: C236 ~ C255
85Vac ~ 264Vac (for normaloperation)
B. Ladder logic for motor operation and to get signal from the floor sensors
The next step of receiving the input signal is to make the motor to operate either up or down direction and the
logic has been developed correspondingly. Figure 8 shows the snap shot of the logic for the motor operation in both
up and down direction. The motor operation is purely based on the input that the PLC gets from the push buttons.
Based on the desired input and corresponding floor, the PLC wil make the motor to stop.
Outputs used for motor operation
1) Up motoring - O:4/1
2) Down motoring- O:4/1
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IJECSE, Volume3, Number 2
Sandar Htay and Su Su Yi Mon
Figure 8. Ladder logic for motor Up and Down operation
C. Ladder logic for floor scan
As an initial move the ladder logic has to be developed for receiving the input signal from the push buttons and
the same is used with the program to get the corresponding output based on this output.
Figure 9 describes the logic that has been developed to get the inputs from the call buttons present at every floor.
When a particulars switch from the corresponding floor has been pressed the program in the PLC gets activated and
the relevant bit will be activated.
Figure 9. Ladder logic for scan floor
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C.Ladderlogic for close and move operation
The process of door closing has to start once the door has been fully opened so a sensor is placed at the end of
door opening and when the sensor is cut a signal will be sent to the PLC. Figure 10illustrates the operation of door
closing once the door opening operation comes to end that is when the sensor present at end for door opening has
been cut. At the end of door closing the sensor will give a signal to the PLC will stop the door motor.
Figure 10. Ladder logic for close and move operation
E. Ladder logic for tracking elevator car movement
Once the operation of the elevator motor ceases the logic has to be developed in such away that it facilitates to
track the elevator car movement. Based on the input from the floor sensors, the program downloaded in the
PLCtotrack the movement. Figure 11 describes the operation of tracking movement. According to the input, the
output O:2/12, O:2/13, O:2/14 and O:2/15 will be activated.
Figure 11. Ladder logic for tracking movement operation
F. Ladder logic for stop and open door operation
The next step receiving the input signalis to stop the motor and then to open the door. After stopping the
condition of motor , the door operation will activate at once. At the end of motor stopping the elevator car, the
sensor will give a signal to the PLC. And then this will open the door motor. Fig 12 express the operation of stop
and open door according to the PLC controller.
Figure 12. Ladder logic for stop and open door operation
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IJECSE, Volume3, Number 2
Sandar Htay and Su Su Yi Mon
Figure 13. GUI result of the complete fourth floors Elevator Control System
V.CONCLUSION
Although some calibrations and requirements may have, the modeling PLC based on elevator control system is
done. The traditionally used relays and IC boards have been replaced by PLC for easy and cheap controlling of
machines used in this elevator. By developing this proposed system,the result of elevator control system can be
applied in the real world. By using PLC based elevator control system, the desired position can be forecasted. The
simulation results of the four floors system have been discussed.As a future work, IVC1 1410MAT PLC based
elevator model is intended to construct and tested to be applicable in the real world.
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