Programmable Logic Controller’s (PLC’s) are small single-purpose computers. They control machines and are common in cars. You probably own more PLC’s than any other type of computer. Today, a single-car has a myriad of PLC’s, usually networked together. PLC’s replace hard-coded wiring, automating tasks.
PLC’s often read input from analog sensors. Responding to temperature, sensing a pedal or a handle, then causing a machine to do something are typical PLC functions.
GM’s automatic transmission was the first application of a PLC. Bedford Associates won a Request for Proposal (RFP) and the lead engineer was Disk Morley.
Besides cars, PLC’s are a common and vital component of modern factories, elevators, and all manner of heavy machinery that repeats the same task.
Because PLC’s are limited in function, they are also typically extremely inexpensive.