The PLC or programmable logic controller was created because of the needs of the American automotive manufacturing industry. Programmable logic controllers were originally adopted by the automotive industry where changing software replaced the re-wiring of hard-wired control panels when production needs changed.
Prior to the PLC, sequencing, control, and safety interlock logic for manufacturing automobiles was done by using hundreds or thousands of cam timers, relays, and drum sequencers as well as dedicated closed-loop controllers. Electricians needed to individually rewire all relays. Updating these facilities for the yearly model switch-over was extremely time consuming and quite expensive.
In 1968 GM Hydramatic, the automatic transmission division of General Motors, issued a request for proposal for an electronic replacement for their hard-wired relay systems. A winning proposal came from Bedford Associates of Bedford, Massachusetts was designated the 084 because it was Bedford Associates’ eighty-fourth project. UPon successful deployment of their newly invented devices, Bedford Associates started a new company dedicated to this new product: Modicon, which stood for MOdular DIgital CONtroller.
The automotive industry is still one of the largest users of PLCs and PQBattery is one of the main suppliers of the batteries that store the programs that run programmable logic controllers.