Simplified red/green traffic light with cross walk help.

[KE0GPL]

Hello everyone. This is my first post to the forums and I came here looking for some help on a ladder diagram.

Okay so what I'm trying to do is make a traffic light that only uses the red and green lights. I want it to where when I press a pushbutton(like at a crosswalk) it'll immediately turn off the green light(that's normally on) and turn the red light on for 20 seconds (so people can walk) and then turn back to green. I Need to use a dpdt timer relay. But I'm not sure what else.

I want the most basic form possible If anyone is willing to help so that I can learn from it and build it to be better myself. Thanks for reading!

 

[janner_10]

Using a timer relay you won't need a PLC. If you use a PLC, you wont need a timer relay.

Which is it for clarity?

 

[KE0GPL]

My apologies. What I'm actually needing help with is the ladder diagram for the control circuit I'm having issues designing. I'm using a simulator control panel.

 

[jrwb4gbm]

If you have RSLogixPro software, I found 7 traffic light examples in the Downloads section. It is accessible thru a button towards the top left of the webpage or this link below.
Link:
http://www.plcs.net/downloads/index.php?&direction=0&order=&directory=Allen_Bradley

If you don't have the LogixPro software, please post back and someone will convert them to .pdf form. Just indicate which one you might need.

 

[KE0GPL]

At this point in time I'm using a simulator by amtrol. I have not get gotten to the actual programming or the plc on this specific simulator yet. I was trying to draw out the ladder diagram first but I kept running into small little issues. Thanks for your replies btw, I was really amazed at how quick everyone was to help. Love this group already. Hopefully before too long I'll be able to contribute and answer other people's questions.

 

[gclshortt]

http://accautomation.ca/building-a-plc-program-that-you-can-be-proud-of-part-1/

http://accautomation.ca/click-plc-drum-instruction/

The above are a couple of examples of how you can write your traffic light program. The first link will walk you through using timers only, then go into indirect addressing for the light control.

Regards,

 

[KE0GPL]

Just wanted to let everyone that commented know that I got it all figured out. It was actually quite simplistic after taking some more time to think it through. My problem was I needed the timer relay before my latching circuit. And then I just energized the CR after the latch then for the red lamp, green lamp, and the energizing of the timer relay I used the N.C. and N.O contacts of the CR to control them.