Breaks algebraic loops by an infinitesimal time delay
Modelica Standard Library
This block delays the Boolean input by an infinitesimal time delay and therefore breaks algebraic loops. In a network of logical blocks, in every closed connection loop at least one logical block must have a delay because algebraic systems of Boolean equations are not practically solvable. The Pre block returns the value of the input signal from the last event iteration. Event iteration stops when both values are identical (u=pre⁡u).
Boolean input signal
Boolean output signal
Start value of pre(u) at initial time
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Boolean Signal Blocks
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