Huntington John III

Programmable Logic Controllers


A Yale Repertory Theatre production of Kiss of the Spider Woman had a large, 2500-pound wagon that needed to be automated. Our usual drive method — a floor-mounted winch frame and a maze of muling blocks — was ruled out because of the shortness of the load-in time in touring. To meet these constraints, we built a unit whose self-contained drive consisted of a speed-controlled motor and a horizontal loop of roller chain, and whose stop points would be set by adjustable-position limit switches mounted in slots milled into the unit’s frame.

In place of a system of relays, we decided to use our Programmable Logic Controller (PLC) to control this system. Even though this particular application ...

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