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Example Ladder Logic Diagram. The schematic diagrams for relay logic circuits are often called line diagrams, because the inputs and outputs are essentially drawn in a series of lines. A relay logic circuit is an electrical network consisting of lines, or rungs, in which each line or rung must have continuity to enable the output device. A ...
Ladder logic is widely used to program PLCs, where sequential control of a process or manufacturing operation is required. Ladder logic is useful for simple but critical control systems or for reworking old hardwired relay circuits. As programmable logic controllers became more sophisticated it has also been used in very complex automation systems.
A relay allows circuits to be switched by electrical equipment: for example, a timer circuit with a relay could switch power at a preset time. For many years relays were the standard method of controlling industrial electronic systems. A number of relays could be used together to carry out complex functions (relay logic). The principle of relay ...
A simple example of an effectively random cause in a physical system is a borderline electrical connection in the wiring or a component of a circuit, where (cause 1, the cause that must be identified and rectified) two conductors may touch subject to (cause 2, which need not be identified) a minor change in temperature, vibration, orientation ...
A solid state relay (SSR) is an electronic switching device that switches on or off when an external voltage (AC or DC) is applied across its control terminals. They serve the same function as an electromechanical relay , but solid-state electronics contain no moving parts and have a longer operational lifetime.
For example, in an induction type electromechanical relay, the time delay for the switching action can be adjusted by adjusting the distance traveled by the disc, whereas in a static relay the delay can be set by adjusting the value of the resistance in an R-C time delay circuit. Static relays may be based on analog solid state circuits ...
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Race condition in a logic circuit. Here, ∆t 1 and ∆t 2 represent the propagation delays of the logic elements. When the input value A changes from low to high, the circuit outputs a short spike of duration (∆t 1 + ∆t 2) − ∆t 2 = ∆t 1.