First, a sketch:
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Ah, yes, and let's list the inputs and outputs:
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Next, a sequence of events:
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After that comes the ladder logic:
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Programming it in (and a little troubleshooting, like realizing we didn't put in the work bits) and it was ready to roll. Take a look:
When I got to my car after class, I realized I did have a camera in my brief case so I ran back in and captured the moment. Too bad the guys were gone by then. Anyway, this is way too much fun.