I am struggling with ladder diagram for traffic light. Is there a systematic way to get the solution?
I don't know if Karnaugh map works here. I have searched a lot but there is not a complete guide on this.

 

Are you familiar with the finite-state machine? It might help you get it done.

 

Yes, not good but I have used it many times. I have seen flow charts used in some books.
Did that what you mean?
By the way, can I use karnaugh map here?

 

When one can end up with hundreds of rungs on a ladder diagram it would become difficult to envisage how a Karnaugh map would assist in the design. Add the complexity of timers, counters, computational blocks and HMI's and you have a grander design to accomplish. The matter of knowing the required system state at the completion of each execution cycle is a key factor as is the verification & testing of those states.
Experience is therefore important and also studying how other designers do this work is helpful. PLC manufacturers may offer training courses.

 

I also use PLC in my job and I never see any PLC programmer witch use karnaugh map.
All you need is experience and split the "problem" into small pieces.

 

Thanks everyone.
I thought that there is a systematic way to solve most of problems. I saw my professor struggling for a while to complete a ladder for traffic light. That made me wonder how can I do it well as even my prof also had to go through it four or five times before got it right.

 

One often recommended way to start is the flow chart method.
Max.

 

one way to symplify the trafic control light timer is to use the master clock. a simple store and compare to control whitch light is on. much easier than using a bunch of timers. just run a counter off the 1 second clock, then compare the count with presets to determine the output to turn on.