Pre

Breaks algebraic loops by an infinitesimal small time delay (y = pre(u): event iteration continues until u = pre(u))

    Pre

Library

Modelica/Blocks/Logical

Description

This block delays the Boolean input by an infinitesimal small time delay andtherefore 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 thelast "event iteration". The "event iteration" stops, once bothvalues are identical (u = pre(u)).

Parameters

Pre_0

NameLabelDescriptionData TypeValid Values

mo_pre_u_start

pre_u_start

Start value of pre(u) at initial time

Scalar

true
false

Pre_1

NameLabelDescriptionData TypeValid Values

mo__nmodifiers

Number of Modifiers

Specifies the number of modifiers

Number

mo__modifiers

Modifiers

Add new modifier

Structure

mo__modifiers/varname

Variable name

Cell of strings

mo__modifiers/attribute

Attribute

Cell of strings

'start'
'fixed'

mo__modifiers/value

Value

Ports

NameTypeDescriptionIO TypeNumber

u

implicit

Connector of Boolean input signal

input

1

y

implicit

Connector of Boolean output signal

output

1