ET 472  LAB 1
PLC CONTROL OF AN ALARM SYSTEM
PURPOSE:  The purpose of this laboratory exercise is introduce students to PLC ladder logic programming using the
Siemens 224 series PLC and MicroWin software.Procedures for developing ladder logic, editing rungs, and simulating circuits will be covered.  Students will develop a control program for an alarm system using standard functions.  A ladder logic program covering basic inputs, outputs and latches and timers will be constructed, simulated, downloaded and executed on a live 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

LADDER LOGIC
SCAN CYCLE
INPUTS
OUTPUTS
LATCH
TON TIMER
ADDRESSING
SIEMENS 224 PLC
MICROWIN SOFTWARE
SYSTEM REQUIREMENTS

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).