Traffic exercise 1

[amhd90]

Hello,
I am trying to resolve traffic simulation exercise 1 where we have:

Light O:2/00 (Red) = 12 seconds ON
Light O:2/02 (Green) = 8 seconds ON
Light O:2/01 (Amber) = 4 seconds ON
The sequence now repeats with Red = ON.

For simplicity, I eliminated amber color for now. I made a ladder logic for green and red with two timers. First, basically it sounds good ?
Secondly, i cant make the timers to reset, so they can start up again continuously.
Any Help ?

 

[amberman]

You could have an overall cycle timer of 24s auto resetting (i.e. use a NC of the timer DN bit) then switch the various lights on and off using LIM testing the timer TT value.

e.g.:

Between 0 and 12-> Red on
Between 13 and 20 -> Green on
Between 21 and 24 - > Amber on

Tweak to get timings right.

(You've got no Red/Amber, I suppose that's a British thing? But it's easily added if you follow the above method)

 

[amhd90]

You could have an overall cycle timer of 24s auto resetting (i.e. use a NC of the timer DN bit) then switch the various lights on and off using LIM testing the timer TT value.

e.g.:

Between 0 and 12-> Red on
Between 13 and 20 -> Green on
Between 21 and 24 - > Amber on

Tweak to get timings right.

(You've got no Red/Amber, I suppose that's a British thing? But it's easily added if you follow the above method)

So one timer with a limit test
when t=12 close red open green and etc... ok i get it, but in the exercise they told to use 2 or more timers in cascade. and i want to resolve as in the exercise first. And I found it
Finally. I just add a final rung shown in figure below and voil†a. Now I will re-do it with three lamp colors and post the solution here or in the upload/download section.