Question Details

Please complete Week-6 Lab Worksheet available in Canvas (Files) and submit in Modules, under week 6 Lab

Do Not Submit This Lab Instructions

Objective

The objective of this lab is to use compare instructions to program a traffic light sequence for both one-way and two-way intersections.

Software

PLC Simulation Software LogixPro available in Citrix Server Lab

Process: The process starts by pressing a NO push button and can be stopped at any time by pressing a NC push button. The process is a simulation of a street traffic light in which a green light lasts for 10 seconds, followed by a yellow light for three seconds, and finally a red light for 10 seconds. The cycle continues until the process is terminated by pressing the stop push button.

Prelab

In the following program, the timer instruction is set for 23 second (230 increments of 0.1 seconds each.) Notice that an XIO instruction with address T4:0/DN is placed before the timer instruction. When DN reaches 230 it becomes true, XIC T4:0/DN becomes false, the timer resets, DN becomes false, XIO T4:0/DN becomes true, and the timer starts counting again. So, basically the timer counts for 23 seconds, resets itself, and starts counting again indefinitely until the process is stopped.

Now we add a series of compare instructions to create the traffic light sequence. Here is some notes:

·         To references the timer we use the instruction T4:0/DN.

·         To reference the accumulator value at any given time we use: T4:0.ACC.

·         Instruction LEQ below is true when the accumulator value is between zero and less than or equal to 100. So, the green light is on.

·         Instructions GRT and LES are true when 100 < Accumulator value < 130. So, the yellow light is on.

·         Instruction GEQ is true when the accumulator value is greater than 130. So, the red light is on.

This is indeed a simpler program than the one we used last week.

Lab Procedure

STEP 1

Enter the above ladder logic program in LogixPro, run the simulation, and verify the functionality of the program. Change the label for the Red light to your name, scan, and attach to Week-6 Lab Worksheet available in the Files.

STEP 2

Modify the above program for a two-way intersection and verify the operation. Scan the program and attach to your Week-6 Lab Worksheet.

STEP 3

Modify the program so that when one side is red and the other side is about to turn from yellow to red, both sides remain red for 2 second. This will avoid crashes. Actually this is the case for actual traffic lights at the intersections. Scan the program and attach to your Week-6 Lab Worksheet.

STEP 4

(Optional) Modify the program in step 3, to turn into a flashing yellow on one side and flashing red on the other side after 2 minutes of normal operation. The flashing rate should be one second on and one second off. This simulates the traffic light at some intersections past midnight. Scan the program and attach to your Week-6 Lab Worksheet.

Lab Report:

Complete Week-6 lab Worksheet available under the Files (Week-6 Lab Folder), then go to Modules, and under Lab assignment submit your lab report.