I'm trying to solve a problem for school by converting a state diagram to a logic circuit then converting that to ladder logic. I've already solved the problem by brute force, but I want to develop a systematic approach. My labs will be only be getting more complex. Of course as I go beyond 6 inputs then I will automate the process using matlab.

The process is fairly clear if not that easy to do. I've been following this guide:

http://faculty.etsu.edu/tarnoff/ntes2150/statemac/statemac.htm

I end up with a circuit using D flip-flops. However, its never explained where the clock signal comes from. How do I implement a clock signal using relay logic?

I think the answer is on this page, but I don;t get it:

http://www.allaboutcircuits.com/vol_4/chpt_10/5.html

Thanks, Scooby

 

You use a timer relay. Timer relays come in many varieties; some delay closing after a signal is applied, some delay open after signal is removed, some generate a pulse when signal is applied, etc. Some contain electronic circuits to handle the timing, some use a pneumatic cylinder with orifice valve to control timing.

 

But the timer implements an edge detector, its not the clock itself. I'm assuming that if you hooked up a normally open push button in place of the C contact then that could be your clock signal. I guess I've been thinking of the clock as synchronous whereas the real world processes are asynchronous.

I'm going to work on that now. I'll post updates as I go along.