PLC for ON/OFF operation Page
Perform Delay operation
Experiment no. 1 SEMISTER I Rev.: 00 Date:
Title: a) Interfacing of lamp & button with PLC for ON & OFF operation.
b) Performed delayed operation of lamp by using Push Button.
Aim: To develop the ladder diagram of lamp & button with PLC for ON & OFF operation &
delayed operation of lamp by using Push Button.
Equipment:
1. PLC trainer Kit- Digital + Analog 14 DI 10 DO 2 AI 2AO
2. Ladder programming software.
3. Communication Cable
4. PC
5. Live Demo Models Interface with PLC & Lamp & Switches Interface.
PLC trainer Kit:
Allen Bradley Micrologix 1200 PLC. 14 Digital inputs, 10 Digital outputs, 2 Analog
inputs, 2 Analog outputs, Built in DC regulated power supply for interface modules. Start, stop
& input simulation switches. Input/output terminations on self oriented latches mini DIN round
connectors. 230 Vac mains socket with inbuilt fuse protection, spare fuse and self illuminated
mains switch. Provision to connect computer via 9 pin D RS232C serial communication port.
MS fabricated, Siemens/ Munshell gray powder painted enclose. Demo modules ladder selection
through toggle input switches. All inputs & outputs available on MS connectors for interface
with user retrofit of any system/project.
Theory:
The 1st PLC system involved from conventional computers in the late 1960s & early
1970s. The PLC keyboard programming procedure replaced the rewiring of a panel full of wires,
relay, timers, counters & other control panel components. The PLC operator essentially draws
the lines and devices of ladder diagrams. The resulting drawing takes the place of much of the
external wiring required for control of a process. The PLC can be operated on the input side by
on-off devices or by variable input devices. i.e. push buttons, toggle switches, limit switches,
relay auxiliary contacts, proximity switches & various sensors & transducer etc.
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ELECT/EMI-D-05 PLC for ON/OFF operation Page 2/10
Perform Delay operation
Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
The PLC system offers the following advantages as compared to electromechanical relays:
1. Simple programming
2. Program changes without system intervention
3. Simple, more cost effective & more reliable
4. Simple & low maintenance cost
5. High reliability & maintainability
6. Small physical size
7. Ability to communicate with computers,
8. Economy
9. Rugged construction
10. Modular design
Areas of Applications of the PLC:
Every system has a controller. Depending on the type of technology used the controllers can be
divided into pneumatic, hydraulic, electrical, electronic controllers. Frequently a combination of
different technologies is used. Differentiation is made between the hard-wired programmable &
PLCs.
Hard-wired programmable are used is out of equation and the job size warrants the developed of
a special controller. Typical application for such controllers can be found in automatic washing
machines, video cameras & car automation.
The 1st PLCs were mostly installed in automotive plants. Traditionally, the auto plants had to be
shut down for up to a month at model changeover time. The early PLCs were used along with
new other automation techniques to shorten the changeover time & reduced programming time
to a matter of a few days.
The original task of a PLCs involved the interconnection of input signals according to a specified
program and, if “true”, to switch the corresponding output. Boolean algebra forms the
mathematical basis for this operation; which recognizes precisely two defined statuses “0” and
“1”. For instance, a motor could therefore be either switched on or off.
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Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
Many PLCs can be expanded by means of additional I/P and O/P analog, positioning and
communication modules. Special PLCs are available for safely technology, shipping or mining
tasks. Finally, PLCs are coupled with other automation components, thus creating considerably
wider areas of applications.
Basic Design of PLC:
The term ‘Programmable Logic Controller’ can be defined as follows:
“A digitally operating electronic system, designed for use in an environment, which uses a
programmable memory for the internal storage of user-oriented instructions for implementing
specific functions such as logic, sequencing, timing, counting, arithmetic, to control , through
digital or analog input & output, various types of machines or processors. Both the PLC and its
associated peripherals are designed so that they can be easily integrated into an industrial control
system and easily used in all their intended functions”.
Fig no. 1 shows, in block form, the system components of a PLC:
POWER SUPPLY
INPUT MODULS OUTPUT MODULES
CENTRAL PROCESSING UNIT
e.g. SWITHCHES, PUSH e.g. RELAYS,MOTORS
PROGRAMMER / MONITOR
Fig. SYSTEM COMPONENTS OF PLC
The function of the input module is to convert incoming input signals into signals, which can be
processed by the PLC, and to pass these to the central processing unit. The input module has
terminals into which the user connects outside process input signals.
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Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
The reverse task is performed by the output module this PLC signal into signal suitable for the
output actuators. The output module has another set of terminals that connects action signals to
the process. The actual processing of the signals is effected in the central processing unit in
accordance with the program stored in the memory.
Memory unit is the library where the program is stored.
Power supply converts AC line voltages to DC for operation of different values. The power
supply also purifies and regulates the DC voltage to ensure proper PLC operation. It drives the
I/O logic signals the CPU, the memory unit and some peripheral devices.
Programmer allows the interface between the PLC and the user during the star up, program
development and troubleshooting. It is the keyboard on which the user the monitor types the
program instructions is a screen on which the typed or operating information is displayed.
Procedure:
A) Precautions:
Ensure following points for proper functioning of the trainer.
Mains supply is 1-ф 230VAC ±10% 50 Hz
All input simulation switches are in off position [Toggle to PLC (up side) side].
At power on no any module is interfaced.
Self illuminated mains switch is off.
B) Experimental Procedure:
1. Ensure mains supply is 1-ф 230VAC ±10% 50 Hz
2. Connect the mains cable and turn ON the self-illuminated mains switch.
3. Ensure the mains switch illuminated and the power on LED on the PLC module lit.
4. Toggle the input simulation switches and observe the appropriate input LED lit.
5. Similarly test the Start and Stop Push Button inputs.
6. Select the appropriate program, connect the individual module as desired and execute
the program & study the module.
C) Shut down procedure:
1. Disconnect all interfacing module / devices.
2. Switch off mains and remove mains cable.
3. Store the trainer along with all accessories in safe custody.
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Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
Ladder Diagram:
A special schematic representation of the hardware and its connection has been developed that
makes combination of the hardware and event sequence description clear. This schematic
representation is called a ladder diagram. It is an outgrowth of early controllers that operated
from AC lines and used relay as the primary switching elements. It is called a ladder diagram
because the various circuit devices connected in parallel across as the AC line from something
that looks like a ladder, with each parallel connection a “rung” on the ladder. The vertical rails
indicate the power source, while the horizontal and vertical line indicates the possible current
flow.
Ladder logic instructions:
This instruction (also called “examine on” or “normally opened”) functions as an input or storage
kit.
If the corresponding memory bit is a “1” (on). This instruction will allow rung continuity and
outputs will energized.
Examines if Open (XIO)]/[
This instruction (also called “examine off” or “normally closed”) functions as an input or storage
kit.
If the corresponding memory bit is a “1” (on), this instruction will not allows rung continuity and
output on its rung will be de-energized the corresponding memory bit is a “0” (off), this
instruction will assume its normal status and allow rung continuity and output on the rung will
energized.
Output Energies (OTE) ()
This instruction sets the specified bit when rung continuity is achieved (rung goes true). Under
normal operating conditions, if the set bit corresponds to an output device, the output device will
be energized when the rung goes true.
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Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
Operational Procedures
For our purposes, input addresses have the form like I:e/b
Similarly output addresses have the form like O:c/b
Where I- Input data file
O-Output data file
: -Element or slot delimiter
e-slot no. of the i/p module
c- Slot no. of the o/p module
b-Bit or terminal delimiter
Example: I:0/1 (input, slot 0, terminal 1)
O:0/6 (output, slot 0, terminal 5)
Getting started with ladder diagram:
1st Open the ladder programming software Allen Bradley RS LOGIX 500 PLC. In this s/w
window, select “New” option in ‘File’ menu for writing new program. Select the processor type
as required such as Micrologix 1000.
All the ladder instructions and its addressing are given in the ‘Help’ menu of ladder
programming s/w.
Always write ladder in offline mode & then download program into the PLC. Turn the PLC in
RUN mode, as while programming it is in program mode.
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Perform Delay operation
Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
Programming the Ladder:-
a) Interfacing of lamp & button with PLC for ON & OFF operation.
Fig 1: in above figure the button is OFF position i.e. normally open hence lamp is OFF.
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Perform Delay operation
Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
Fig 2: in above figure the button is ON position i.e. normally closed hence lamp is ON.
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Perform Delay operation
Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
b) Delayed operation of lamp by using push button
Fig: in above figure the push button is OFF position i.e. normally open & lamp is OFF thus
delayed operation does not perform.
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Perform Delay operation
Experiment no. 1 SEMISTER I Rev.: 00 Date: 16-06-15
Fig: in above figure the push button is ON position i.e. normally closed & lamp is ON i.e.
delayed operation performing & lamp will ON after 10sec.
Conclusion: Thus we have studied the basic ladder logic instruction and function. So also, we
have studied the interfacing of lamp and button with PLC for on-off operation by using push
button we have performed the delay operation
Signature of Staff: Grade:
Date:
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