A group of interconnected logic elements that act in combination to perform a relatively complex logic function. Programming-recording system constructed of solid-state modules based on a series of binary logic (go/no go) components. A pneumatic or electronic system composed of relays, solid-state electronic logic modules, fluidic logic elements, PLCs or DCSs which solves complex problems of interlocking or sequencing through the repeated use of simple functions that define basic concepts such as OR and AND gates.
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