Modelica.Blocks.Logical

Information

This package provides blocks with Boolean input and output signals to describe logical networks. A typical example for a logical network built with package Logical is shown in the next figure:

The actual value of Boolean input and/or output signals is displayed in the respective block icon as "circle", where "white" color means value false and "green" color means value true. These values are visualized in a diagram animation.

Package Content

Name	Description
And	Logical 'and': y = u1 and u2
Or	Logical 'or': y = u1 or u2
Xor	Logical 'xor': y = u1 xor u2
Nor	Logical 'nor': y = not (u1 or u2)
Nand	Logical 'nand': y = not (u1 and u2)
Not	Logical 'not': y = not u
Pre	Breaks algebraic loops by an infinitesimal small time delay (y = pre(u): event iteration continues until u = pre(u))
Edge	Output y is true, if the input u has a rising edge (y = edge(u))
FallingEdge	Output y is true, if the input u has a falling edge (y = edge(not u))
Change	Output y is true, if the input u has a rising or falling edge (y = change(u))
GreaterThreshold	Output y is true, if input u is greater than threshold
GreaterEqualThreshold	Output y is true, if input u is greater or equal than threshold
LessThreshold	Output y is true, if input u is less than threshold
LessEqualThreshold	Output y is true, if input u is less or equal than threshold
Greater	Output y is true, if input u1 is greater than input u2
GreaterEqual	Output y is true, if input u1 is greater or equal than input u2
Less	Output y is true, if input u1 is less than input u2
LessEqual	Output y is true, if input u1 is less or equal than input u2
ZeroCrossing	Trigger zero crossing of input u
LogicalSwitch	Logical Switch
Switch	Switch between two Real signals
Hysteresis	Transform Real to Boolean signal with Hysteresis
OnOffController	On-off controller
TriggeredTrapezoid	Triggered trapezoid generator
Timer	Timer measuring the time from the time instant where the Boolean input became true
RSFlipFlop	A basic RS Flip Flop
TerminateSimulation	Terminate simulation if condition is fulfilled

Modelica.Blocks.Logical.And

Information

The output is true if all inputs are true, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Or

Information

The output is true if at least one input is true, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Xor

Information

The output is true if exactly one input is true, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Nor

Information

The output is true if none of the inputs is true, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Nand

Information

The output is true if at least one input is false, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Not

Information

The output is true if the input is false, otherwise the output is false.

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Pre

Information

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)).

Parameters

Name	Description
pre_u_start	Start value of pre(u) at initial time

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Edge

Information

The output is true if the Boolean input has a rising edge from false to true, otherwise the output is false.

Parameters

Name	Description
pre_u_start	Start value of pre(u) at initial time

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.FallingEdge

Information

The output is true if the Boolean input has a falling edge from true to false, otherwise the output is false.

Parameters

Name	Description
pre_u_start	Start value of pre(u) at initial time

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Change

Information

The output is true if the Boolean input has either a rising edge from false to true or a falling edge from true to false, otherwise the output is false.

Parameters

Name	Description
pre_u_start	Start value of pre(u) at initial time

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.GreaterThreshold

Information

The output is true if the Real input is greater than parameter threshold, otherwise the output is false.

Parameters

Name	Description
threshold	Comparison with respect to threshold

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.GreaterEqualThreshold

Information

The output is true if the Real input is greater than or equal to parameter threshold, otherwise the output is false.

Parameters

Name	Description
threshold	Comparison with respect to threshold

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.LessThreshold

Information

The output is true if the Real input is less than parameter threshold, otherwise the output is false.

Parameters

Name	Description
threshold	Comparison with respect to threshold

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.LessEqualThreshold

Information

The output is true if the Real input is less than or equal to parameter threshold, otherwise the output is false.

Parameters

Name	Description
threshold	Comparison with respect to threshold

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Greater

Information

The output is true if Real input u1 is greater than Real input u2, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.GreaterEqual

Information

The output is true if Real input u1 is greater than or equal to Real input u2, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Less

Information

The output is true if Real input u1 is less than Real input u2, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.LessEqual

Information

The output is true if Real input u1 is less than or equal to Real input u2, otherwise the output is false.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.ZeroCrossing

Information

The output "y" is true at the time instant when the input "u" becomes zero, provided the input "enable" is true. At all other time instants, the output "y" is false. If the input "u" is zero at a time instant when the "enable" input changes its value, then the output y is false.

Note, that in the plot window of a Modelica simulator, the output of this block is usually identically to false, because the output may only be true at an event instant, but not during continuous integration. In order to check that this component is actually working as expected, one should connect its output to, e.g., component ModelicaAdditions.Blocks.Discrete.TriggeredSampler.

Connectors

Name	Description
y	Connector of Boolean output signal
u
enable	Zero input crossing is triggered if the enable input signal is true

Modelica.Blocks.Logical.LogicalSwitch

Information

The LogicalSwitch switches, depending on the Boolean u2 connector (the middle connector), between the two possible input signals u1 (upper connector) and u3 (lower connector).

If u2 is true, connector y is set equal to u1, else it is set equal to u3.

Connectors

Name	Description
u1	Connector of first Boolean input signal
u2	Connector of second Boolean input signal
u3	Connector of third Boolean input signal
y	Connector of Boolean output signal

Modelica.Blocks.Logical.Switch

Information

The Logical.Switch switches, depending on the logical connector u2 (the middle connector) between the two possible input signals u1 (upper connector) and u3 (lower connector).

If u2 is true, the output signal y is set equal to u1, else it is set equal to u3.

Connectors

Name	Description
u1	Connector of first Real input signal
u2	Connector of Boolean input signal
u3	Connector of second Real input signal
y	Connector of Real output signal

Modelica.Blocks.Logical.Hysteresis

Information

This block transforms a Real input signal into a Boolean output signal:

• When the output was false and the input becomes greater than parameter uHigh, the output switches to true.
• When the output was true and the input becomes less than parameter uLow, the output switches to false.

The start value of the output is defined via parameter pre_y_start (= value of pre(y) at initial time). The default value of this parameter is false.

Parameters

Name	Description
uLow	if y=true and u<=uLow, switch to y=false
uHigh	if y=false and u>=uHigh, switch to y=true
pre_y_start	Value of pre(y) at initial time

Connectors

Name	Description
u
y

Modelica.Blocks.Logical.OnOffController

Information

The block OnOffController sets the output signal y to true when the input signal u falls below the reference signal minus half of the bandwidth and sets the output signal y to false when the input signal u exceeds the reference signal plus half of the bandwidth.

Parameters

Name	Description
bandwidth	Bandwidth around reference signal
pre_y_start	Value of pre(y) at initial time

Connectors

Name	Description
reference	Connector of Real input signal used as reference signal
u	Connector of Real input signal used as measurement signal
y	Connector of Real output signal used as actuator signal

Modelica.Blocks.Logical.TriggeredTrapezoid

Information

The block TriggeredTrapezoid has a Boolean input and a real output signal and requires the parameters amplitude, rising, falling and offset. The output signal y represents a trapezoidal signal dependent on the input signal u.

The behaviour is as follows: Assume the initial input to be false. In this case, the output will be offset. After a rising edge (i.e., the input changes from false to true), the output is rising during rising to the sum of offset and amplitude. In contrast, after a falling edge (i.e., the input changes from true to false), the output is falling during falling to a value of offset.

Note, that the case of edges before expiration of rising or falling is handled properly.

Parameters

Name	Description
amplitude	Amplitude of trapezoid
rising	Rising duration of trapezoid [s]
falling	Falling duration of trapezoid [s]
offset	Offset of output signal

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Real output signal

Modelica.Blocks.Logical.Timer

Information

When the Boolean input "u" becomes true, the timer is started and the output "y" is the time from the time instant where u became true. The timer is stopped and the output is reset to zero, once the input becomes false.

Connectors

Name	Description
u	Connector of Boolean input signal
y	Connector of Real output signal

Modelica.Blocks.Logical.RSFlipFlop

Information

The output Q is set by the input S and reset by the input R, and keeps its value in between. QI is the inverse of Q.

Parameters

Name	Description
Qini	Start value of Q at initial time

Connectors

Name	Description
Q
QI
S
R

Modelica.Blocks.Logical.TerminateSimulation

Information

In the parameter menu, a time varying expression can be defined via variable condition, for example "condition = x < 0", where "x" is a variable that is declared in the model in which the "TerminateSimulation" block is present. If this expression becomes true, the simulation is (successfully) terminated. A termination message explaining the reason for the termination can be given via parameter "terminationText".

Parameters

Name	Description
condition	Terminate simulation when condition becomes true
terminationText	Text that will be displayed when simulation is terminated

Connectors

Name	Description
condition	Terminate simulation when condition becomes true