LogixPro Traffic Light with Dual Delayed Red

Solution example of the LogixPro Traffic Light simulation for the extra credit project given to EMEC240/PTRT5082 students at Northampton Community College, Bethlehem, PA. Note: Audio is not the best quality and I did not work from a script, so it's a-bit rough.

Category:

Education

Tags:

• LogixPro
• Simulation
• Traffic Light

[jtodora]

Whether you use cascading timers or comparison instructions depends upon what the student is learning. The first method is to use cascading timers, then when introducing comparison instruction do the exercise again using one timer and comparisons. You can also do it again using the sequencer out instruction. It all depends upon what lesson you are learning.

[ssj4majinmatt]

How did you get it to work, i've been doing this for days, it is for extra credit and i can't figure the damn thing out

[jtodora]

@ssj4majinmatt

I will not provide a solution but one method is to use one timer with a preset value that covers the total length of time for Red to Yellow to Green. Then, use comparison instruction using the timer accumulator to turn on the appropriate light at the appropriate time. That's just one way to do it. You could also use individual timers in a cascading method to control the light sequence.

[pm081]

Hey- all your walk signs say dont walk, guess ya dont have that part figured out yet....

How did u do it? With timers- or a sequencer?

[jtodora]

Yes...I know the Don't Walk signs do not work. I assign my students project in phases and this phase was to simply get the light to control traffic. Keep checking back for a full solution.

[cidcarioca]

I´m in this exercise now but dont know how to put a delay of 1 second to the green lights...

Trying about one day and nothing works because the red light O:2/00 begins together a cicle with the green light O:2/06 but the red light light must turn on 1 secound in the previous cycle before the next cycle begins!

I´m going crazy with that. please help me with some tips?

Sorry for my bad english but I´m learning it :)

thanks

[jtodora]

One of the easiest ways to solve a stop light problem is to basically use one timer that is set to the total cycle time of the stop light; (Red-to-Green-to-Yellow-and back to Red). Then use comparison instructions to control the lights.

[Cavaleiro08]

That's the normal way a traffic light works. My ideia is to get it to another level, with a sensor or laser sensor that detects if there is a car on the red or not, if there is not a car, the red light will stay on and the other will have green, unless some pedestrean want's to cross the street. After that, all depends on wich road has more traffic, or if does not have any traffic at all. The results? You won't need to stop on a red light when no one else is on the other road|

[ubadoob]

@jtosora exercise 2 should not be done with comparison instructions as this exercise is to get familiar with cascading timers. Comparisons come later.

[Acetripp]

OR U CAN DO IT WAY EASIER AND U ONE TIMER AND LIMITS

[pm081]

@boniface4jesus . You'll need to learn chapter 12 sequencers. You should be able to do everything in 3 or 4 rungs. Using the sequencer eliminates the possibility of crashes. Hope this helps...3bd

[boniface4jesus]

@pm081 I think I figured out how to at least get the walk/don't signs to change when their corresponding green light does. On the rung with output to the north/south green light O:2/2 I put an output branch, and the output on that branch is for O:2/7. Then on the rung with output to the east/west green light O:2/6 I put an output branch, and the output on that branch is for O:2/3. I am having trouble with how to get the car and pedestrian sensors to work though. Any suggestions?