WOLFRAM SYSTEM MODELER
PreBreaks algebraic loops by an infinitesimal small time delay (y = pre(u): event iteration continues until u = pre(u)) |
SystemModel["Modelica.Blocks.Logical.Pre"]
This information is part of the Modelica Standard Library maintained by the Modelica Association.
This block delays the Boolean input by an infinitesimal small 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, since algebraic systems of Boolean equations are not solvable.
The "Pre" block returns the value of the "input" signal from the last "event iteration". The "event iteration" stops, once both values are identical (u = pre(u)).
pre_u_start |
Value: false Type: Boolean Description: Start value of pre(u) at initial time |
---|
u |
Type: BooleanInput Description: Connector of Boolean input signal |
|
---|---|---|
y |
Type: BooleanOutput Description: Connector of Boolean output signal |
Modelica.Blocks.Examples Demonstrates the usage of logical blocks |
Modelica.Blocks.Logical A basic RS Flip Flop |
|
Modelica.Electrical.PowerConverters.ACDC 2*m pulse thyristor rectifier bridge |
|
Modelica.Electrical.PowerConverters.ACDC 2*m pulse half controlled rectifier bridge |