While the DCS was tailored to meet the needs of large continuous industrial processes, in industries where combinatorial and sequential logic was the primary requirement, the PLC evolved out of
a need to replace racks of relays and timers used for event-driven control. The old controls were difficult to re-configure and debug, and PLC control enabled networking of signals to a central
control area with electronic displays. PLC were first developed for the automotive industry on vehicle production lines, where sequential logic was becoming very complex.[4]
It was soon adopted in a large number of other event-driven applications as varied as printing presses and water treatment plants.