Charles,

Siemens have a product called LOGO! which is a small PLC. Klockner Moeller also have a similar product and I expect quite a few other companies have also. The base model LOGO! is <$100USD with 4 inputs and 4 relay outputs.

As for programming - these things are simplicity themselves -either through the clunky lcd display or via the windows software (much better).
1. New project
2. use timer block
3. use input to trigger timer
4. timer output to relay
5. set time for timer
6. download to PLC
Connect power and contactors. Industrial strength and CE - job done.

To do the same with a micro - choose micro, design circuit, design pcb, get pcb made,assemble, write code,test system.

If you were a contractor and you had to find the fastest, cheapest and most reliable solution, I'm sure the answer is clear. Seems Ricky is spending a lot of time trying to debug the system - is it hardware, software?? - for a contractor on a fixed price job, you've blown your money.

Most of my professional life has been assembler programming and electronic design for industrial and instrumentation controllers and I can say quite categorically that doing most control tasks on a PLC is substancially easier than writing asm on a micro from scratch. Obviously PLCs aren't the be all and end all (if they were, I wouldn't have a job!!) and they are just pre-packaged micros with a canned interpreter.
But they are dropping in price and are hard to beat.

BTW: The Schneider Twido PLC's have a mitsubishi flash micro in them, so you can load your own code into them. Some of the Allen Bradley small plcs use dallas ds80c320's also.


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