traffic light

[sniper123]

i have an question from my teacher to build an ladder diagram for a traffic light

that has only 2 timer and the red light will be on for 30 sec and then the green light will be on for 25 sec and the Amber light will be on for 5 sec
and there is no start button and the sequence repeats itself

please help

 

[Doug-P]

I'll save you some ridicule and suggest you put up something of your own efforts as a starting point.

 

[shooter]

think of a timer that has 25 seconds and the other is 5 sec.
when a green or amber is on the other light is red.
make a flipflop to change direction.
and obvious we will not give the answer

 

[shooter]

look at leftside of doug.

 

[sniper123]

think of a timer that has 25 seconds and the other is 5 sec.
when a green or amber is on the other light is red.
make a flipflop to change direction.
and obvious we will not give the answer

the red light must be on while the other lights are in off condition

 

[sniper123]

I'll save you some ridicule and suggest you put up something of your own efforts as a starting point.

i tried to solved but it is so hard that i cant figure the solution.

 

[Saffa]

i tried to solved but it is so hard that i cant figure the solution.

Show us what you've done. This is not hard at all.

 

[T Gibbs]

Use compare instructions

 

[Helliana]

i tried to solved but it is so hard that i cant figure the solution.

I'm going to save that one to try on my boss one day. That should go over well.

 

[T Gibbs]

This can be done with a single timer by using compare instructions

 

[jrwb4gbm]

I know this is a tough one, so here is a little push. One way to get a 5 second timer, start both timers at the same time and use the time period for when the 25 second timer is done but the 30 second timer is not yet done. Then, reset both timers at 30 seconds.

 

[Pete.S.]

You only need one timer, a 60 second timer. Always counting and when it has counted to 60 it restarts.

When the timer is between 0 and 29 seconds the red light is on,
between 30 and 54 seconds the green light is on and
between 55 and 59 the amber light is on.

That should be about 4 or 5 lines of ladder, depending on what PLC you use.

PS. T Gibbs already mentioned this.

.

 

[Diameter157]

If you are still having trouble, try to google "plc traffic lights". One of the first results is a pdf file which has the whole program.

 

[jvdcande]

If you are still having trouble, try to google "plc traffic lights". One of the first results is a pdf file which has the whole program.

You should also mention that he has to scroll through to pages 26 and 27. Then he'll have his solution without the need to understand what he has done. Unless I'm wrong, of course. But I for one don't want to take any chances and will never agree to work alongside someone who wasn't even able to find such a document in his own time and did his learning this way. My life is way too valuable to me and my loved ones.

 

[Doug-P]

Two days and fourteen posts in and still no effort by the OP.