PURPOSE: The purpose of this laboratory exercise is introduce students to PLC ladder logic programming using theET 472 LAB 1
PLC CONTROL OF AN ALARM SYSTEM
OBJECTIVES: After completing this laboratory exercise you should be able to do the following:
1. Define and identify INPUTS, OUTPUTS,
LATCHES, TIMERS, RUNGS, SCAN CYCLES
related to PLC ladder
logic.
2. Create ladder logic required to control the system using MicroWin software.
3. Simulate the control using input simulator switches to verify program execution.
4. Download the program to a pre wired Siemens 224 PLC for controlling a real-time alarm system.
5. Run the developed program and verify real-time execution.
6. Write a technical laboratory report using
the required format for the class.
KEY TERMS
SYSTEM REQUIREMENTSLADDER LOGIC
SCAN CYCLE
INPUTS
OUTPUTS
LATCH
TON TIMER
ADDRESSING
SIEMENS 224 PLC
MICROWIN SOFTWARE
The system is activated by depressing the "ARM"
switch. The ARM switch will start
a timer and enable the system for motion detection
after a time of 5 seconds has elapsed.
The delay allows the operator to set the system
and exit the area. If the motion detector senses
movement, both the strobe light and
audible siren will be turned on. The system will continue
to activate the strobe and siren until the
DISARM switch is depressed. The system is reset
by the DISARM switch and ready to be "re-armed". The system also must have a test mode
which checks to make sure the audible siren and visual stroke are working correctly. The test
mode is activated by depressing the disarm switch first and holding down the arm switch
simultanuously.
PROCEDURES: The following steps should be taken to complete this laboratory exercise:
1. Specifically define the requirements of the system.
2. Identify all inputs, outputs and timer types and logical addresses as follows:
I/O DESCRIPTION REAL WORLD STATE ADDRESS
INPUT
ARM
SWITCH
NORMALLY
OPEN
I 0.0
INPUT
DISARM SWITCH NORMALLY
OPEN
I 0.1
INPUT
MOTION DETECTOR NORMALLY
CLOSED
I 0.2
TIMER
T 33
OUTPUT STROBE
LIGHT
Q 0.0
OUTPUT
SIREN
Q 0.1
3. Develop a control sequence chart based
on the system requirements
4. Create a wiring diagram showing all inputs power supply and output connections
(refer to the example shown in class).
5. Write the ladder logic on paper, making notes of each network (rung).
6. Using the MicroWin software, enter the
ladder logic and save the file as Lab1.
Note: Save the
file to YOUR disk or CD. Do not save to the hard drive.
Download the program
to the Siemens S7-224 PLC.
7. Using the simulator switches provided
with the 224 PLC, simulate your program
to verify the correct
execution. Note: Monitor the logic states using the Program
Status Option.
8. Download your program to the alarm system
in the automation lab and run to program for testing.
Demonstrate the execution
of your program to your instructor and have it approved
(the instructor will
sign your program verification sheet). Attach this sheet to your
written report.
9. Using the format specified in the syllabus, write a technical lab report including required documentation.
10.Submit your written report by the due date. (One week from the scheduled lab session).