Traffic Light Program Logic

[vcok1973]

I am trying to do a lab in school that involves traffic lights. I would be happy if anyone can help me out with this exercise.
Sincerely,
vcok1973

 

[Steve Etter]

What specifically can we do to help you?

Steve

 

[Ken Moore]

Need more information.
1. What type of PLC or simulator are you writting the logic for.
2. What exactly is your assignment.
3. What have you attempted so far, what does not work, what does.
4. If possible post your current code.

People on the site will help if you try to solve a problem and can't. But will not usually provide the complete answer.

Besides, I'm a firm believer of "learning by doing", so if you do, you learn. If we do we learn. :site:

 

[randylud]

Maybe Phil should add a separate section of the forum just for people with assignments from their courses in school. I for one would be glad to proctor that section, and might even have a few of my students post there. However, I tend to be fairly unforgiving with my students when they try and pull a fast one on me. Usually that happens in the form of, "I don't know what to do, can you help me?" When I say sure and begin to ask them what they have done or thought about on their own to solve the problem, the truth usually surfaces pretty quickly. A typical response is often, "well, I figured you would tell me what to do!" I do not tell people what to do, I only try and help them learn what to do. There is a difference. End of mini-rant.

 

[CaseyK]

Maybe Phil should add a separate section of the forum just for people with assignments from their courses in school.

Well Randy..............you may remember responding to to the Student Posting Section" "THREAD" that I posted on July 29, 2004.

Boy, did I get blasted for suggesting it.

Jim Dungar wrote "Students rarely follow up their original questions so a dedicated area would probably not be used."

We see a lot of "One Post Wonders". time will tell.

Perhaps we just need a "Traffic Light Section".

But if there was a button, would they see it and use it?

regards.....kc

 

[Doug_Adam]

I don't agree that Phil should set aside a student area for any reason.
We are all students, also students have to learn to deal with the "Big Boys" for when they are let loose into the real world....

Now to the question. This is what I think Vcok should do:
1, Draw a picture of your traffic light lay out (your assignment paper may already have given this)
2, Make a list of devices to be controlled (outputs). I.e North south traffic light, East/West traffic light, pedestrian crossing, turn arrows, etc.
3, Make a list of controlling devices (inputs). I.e pedestrian crossing button, light change switch.
4, Make a sequence of steps, each step showing which outputs are on and showing what inputs are needed to jump to the next step. Also remember that you can use internal inputs such as timers to jump to the next step. Don't forget to include a startup step that would only be used on power up. Use a large piece of paper for this, a pencil and eraser. It will be messy when you finish.

The above is usually called a "Functional Specification". It is the hard bit of any project.
Once you have done this and checked it, actual coding is trivial.

 

[saladolf]

i have a simple program i have done for LG PLC if u want i will give to you in PDF format
that will give you a start point then you can proceed