Programmable Logic Controllers

Question 1:

The Programmable Logic Controller, or PLC, was invented in the late 1960's by engineers working for an American company named Bedford Associates. What was the intended purpose of this device, which was then called the MODICON (for MODular DIgital CONtroller)? What applications was it intended to find use in, and why would it be an advantage over existing technology?
Programmable Logic Controllers were (and still are) primarily intended to replace hard-wired relay logic circuits.

Ask your students what advantages programmable devices have over hard-wired circuits. Also ask them to think if there are any disadvantages to programmable devices, as opposed to hard-wired circuits. What types of applications do they think each type of digital technology might find the most use in?

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