Buildings.Controls.Continuous

Package with models for discrete time controls

Information

This package contains components models for continuous time controls. For additional models, see also Modelica.Blocks.Discrete.

Extends from Modelica.Icons.VariantsPackage (Icon for package containing variants).

Package Content

Name Description

LimPID P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting

PIDHysteresis PID controller with anti-windup, output limiter and output hysteresis

PIDHysteresisTimer PID controller with anti-windup, hysteresis and timer to prevent short cycling

SignalRanker Ranks output signals such that y[i] >= y[i+1]

NumberOfRequests Outputs the number of signals that are above/below a certain threshold

OffTimer Records the time since the input changed to false

Examples Collection of models that illustrate model use and test models

Name	Description
LimPID	P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting
PIDHysteresis	PID controller with anti-windup, output limiter and output hysteresis
PIDHysteresisTimer	PID controller with anti-windup, hysteresis and timer to prevent short cycling
SignalRanker	Ranks output signals such that y[i] >= y[i+1]
NumberOfRequests	Outputs the number of signals that are above/below a certain threshold
OffTimer	Records the time since the input changed to false
Examples	Collection of models that illustrate model use and test models

Buildings.Controls.Continuous.LimPID

P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting

Buildings.Controls.Continuous.LimPID

Information

This model is identical to Modelica.Blocks.Continuous.LimPID except that it can be configured to have a reverse action.

If the parameter reverseAction=false (the default), then u_m < u_s increases the controller output, otherwise the controller output is decreased. Thus,

for a heating coil with a two-way valve, set reverseAction = false,
for a cooling coils with a two-way valve, set reverseAction = true.

Extends from Modelica.Blocks.Continuous.LimPID (P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting).

Parameters

Type Name Default Description

SimpleController controllerType Modelica.Blocks.Types.Simple... Type of controller

Real k 1 Gain of controller [1]

Time Ti Time constant of Integrator block [s]

Time Td Time constant of Derivative block [s]

Real yMax 1 Upper limit of output

Real yMin 0 Lower limit of output

Real wp 1 Set-point weight for Proportional block (0..1)

Real wd 0 Set-point weight for Derivative block (0..1)

Real Ni 0.9 Ni*Ti is time constant of anti-windup compensation

Real Nd 10 The higher Nd, the more ideal the derivative block

Boolean reverseAction false Set to true for throttling the water flow rate through a cooling coil controller

Initialization

InitPID initType Modelica.Blocks.Types.InitPI... Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)

Boolean limitsAtInit true = false, if limits are ignored during initializiation

Real xi_start 0 Initial or guess value value for integrator output (= integrator state)

Real xd_start 0 Initial or guess value for state of derivative block

Real y_start 0 Initial value of output

Type	Name	Default	Description
SimpleController	controllerType	Modelica.Blocks.Types.Simple...	Type of controller
Real	k	1	Gain of controller [1]
Time	Ti		Time constant of Integrator block [s]
Time	Td		Time constant of Derivative block [s]
Real	yMax	1	Upper limit of output
Real	yMin	0	Lower limit of output
Real	wp	1	Set-point weight for Proportional block (0..1)
Real	wd	0	Set-point weight for Derivative block (0..1)
Real	Ni	0.9	Ni*Ti is time constant of anti-windup compensation
Real	Nd	10	The higher Nd, the more ideal the derivative block
Boolean	reverseAction	false	Set to true for throttling the water flow rate through a cooling coil controller
Initialization
InitPID	initType	Modelica.Blocks.Types.InitPI...	Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)
Boolean	limitsAtInit	true	= false, if limits are ignored during initializiation
Real	xi_start	0	Initial or guess value value for integrator output (= integrator state)
Real	xd_start	0	Initial or guess value for state of derivative block
Real	y_start	0	Initial value of output

Connectors

Type Name Description

input RealInput u_s Connector of setpoint input signal

input RealInput u_m Connector of measurement input signal

output RealOutput y Connector of actuator output signal

Type	Name	Description
input RealInput	u_s	Connector of setpoint input signal
input RealInput	u_m	Connector of measurement input signal
output RealOutput	y	Connector of actuator output signal

Modelica definition

block LimPID 
  "P, PI, PD, and PID controller with limited output, anti-windup compensation and setpoint weighting"
  extends Modelica.Blocks.Continuous.LimPID(
    addP(k1=revAct*wp, k2=-revAct),
    addD(k1=revAct*wd, k2=-revAct),
    addI(k1=revAct, k2=-revAct),
    yMin=0,
    yMax=1);

  parameter Boolean reverseAction = false 
    "Set to true for throttling the water flow rate through a cooling coil controller";
protected 
  parameter Real revAct = if reverseAction then -1 else 1;
end LimPID;

Buildings.Controls.Continuous.PIDHysteresis

PID controller with anti-windup, output limiter and output hysteresis

Buildings.Controls.Continuous.PIDHysteresis

Information

Block of a controller for set point tracking with a hysteresis element that switches the controller on and off.

If the controller is off, and the control error becomes larger than eOn, then the controller switches to on and remains on until the control error is smaller than eOff. When the controller is on, the set point tracking can be done using a P-, PI-, or PID-controller. In its off-mode, the control output is zero. Thus, the parameters yMin and yMax are used to constrain the output of the controller during its on mode only. This can be used, for example, to modulate a device between 0.3 and 1.0, and switch it to off when the control error is small enough.

Extends from Modelica.Blocks.Interfaces.SVcontrol (Single-Variable continuous controller).

Parameters

Type Name Default Description

Hysteresis

Real eOn 1 if off and control error > eOn, switch to set point tracking

Real eOff -eOn if on and control error < eOff, set y=0

Boolean pre_y_start false Value of hysteresis output at initial time

Set point tracking

SimpleController controllerType Modelica.Blocks.Types.Simple... Type of controller

Real k 1 Gain of controller

Time Ti Time constant of Integrator block [s]

Time Td Time constant of Derivative block [s]

Real yMax 1 Upper limit of output

Real yMin 0 Lower limit of output

Real wp 1 Set-point weight for Proportional block (0..1)

Real wd 0 Set-point weight for Derivative block (0..1)

Real Ni 0.9 Ni*Ti is time constant of anti-windup compensation

Real Nd 10 The higher Nd, the more ideal the derivative block

Boolean reverseAction false Set to true to enable reverse action (such as for a cooling coil controller)

Initialization

InitPID initType Modelica.Blocks.Types.InitPI... Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)

Boolean limitsAtInit true = false, if limits are ignored during initializiation

Real xi_start 0 Initial or guess value value for integrator output (= integrator state)

Real xd_start 0 Initial or guess value for state of derivative block

Real y_start 0 Initial value of output

Type	Name	Default	Description
Hysteresis
Real	eOn	1	if off and control error > eOn, switch to set point tracking
Real	eOff	-eOn	if on and control error < eOff, set y=0
Boolean	pre_y_start	false	Value of hysteresis output at initial time
Set point tracking
SimpleController	controllerType	Modelica.Blocks.Types.Simple...	Type of controller
Real	k	1	Gain of controller
Time	Ti		Time constant of Integrator block [s]
Time	Td		Time constant of Derivative block [s]
Real	yMax	1	Upper limit of output
Real	yMin	0	Lower limit of output
Real	wp	1	Set-point weight for Proportional block (0..1)
Real	wd	0	Set-point weight for Derivative block (0..1)
Real	Ni	0.9	Ni*Ti is time constant of anti-windup compensation
Real	Nd	10	The higher Nd, the more ideal the derivative block
Boolean	reverseAction	false	Set to true to enable reverse action (such as for a cooling coil controller)
Initialization
InitPID	initType	Modelica.Blocks.Types.InitPI...	Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)
Boolean	limitsAtInit	true	= false, if limits are ignored during initializiation
Real	xi_start	0	Initial or guess value value for integrator output (= integrator state)
Real	xd_start	0	Initial or guess value for state of derivative block
Real	y_start	0	Initial value of output

Connectors

Type Name Description

input RealInput u_s Connector of setpoint input signal

input RealInput u_m Connector of measurement input signal

output RealOutput y Connector of actuator output signal

Type	Name	Description
input RealInput	u_s	Connector of setpoint input signal
input RealInput	u_m	Connector of measurement input signal
output RealOutput	y	Connector of actuator output signal

Modelica definition

model PIDHysteresis 
  "PID controller with anti-windup, output limiter and output hysteresis"
  extends Modelica.Blocks.Interfaces.SVcontrol;

  parameter Real eOn = 1 
    "if off and control error > eOn, switch to set point tracking";
  parameter Real eOff = -eOn "if on and control error < eOff, set y=0";
  parameter Boolean pre_y_start=false 
    "Value of hysteresis output at initial time";

  parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PID 
    "Type of controller";
  parameter Real k=1 "Gain of controller";
  parameter Modelica.SIunits.Time Ti "Time constant of Integrator block";
  parameter Modelica.SIunits.Time Td "Time constant of Derivative block";
  parameter Real yMax=1 "Upper limit of output";
  parameter Real yMin=0 "Lower limit of output";
  parameter Real wp=1 "Set-point weight for Proportional block (0..1)";
  parameter Real wd=0 "Set-point weight for Derivative block (0..1)";
  parameter Real Ni=0.9 "Ni*Ti is time constant of anti-windup compensation";
  parameter Real Nd=10 "The higher Nd, the more ideal the derivative block";
  parameter Boolean reverseAction = false 
    "Set to true to enable reverse action (such as for a cooling coil controller)";

  parameter Modelica.Blocks.Types.InitPID initType=Modelica.Blocks.Types.InitPID.DoNotUse_InitialIntegratorState 
    "Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)";
  parameter Boolean limitsAtInit=true 
    "= false, if limits are ignored during initializiation";
  parameter Real xi_start=0 
    "Initial or guess value value for integrator output (= integrator state)";
  parameter Real xd_start=0 
    "Initial or guess value for state of derivative block";
  parameter Real y_start=0 "Initial value of output";

  LimPID PID(
    controllerType=controllerType,
    k=k,
    Ti=Ti,
    yMax=yMax,
    yMin=yMin,
    wp=wp,
    wd=wd,
    Ni=Ni,
    Nd=Nd,
    initType=initType,
    limitsAtInit=limitsAtInit,
    xi_start=xi_start,
    xd_start=xd_start,
    y_start=y_start,
    Td=Td,
    reverseAction=reverseAction) "Controller for room temperature";
  Modelica.Blocks.Logical.Hysteresis hys(
    pre_y_start=pre_y_start,
    uLow=eOff,
    uHigh=eOn) "Hysteresis element to switch controller on and off";
  Modelica.Blocks.Logical.Switch swi;
  Modelica.Blocks.Sources.Constant zer(k=0) "Zero signal";
  Modelica.Blocks.Math.Feedback feeBac;
  Modelica.Blocks.Logical.Switch swi1;

equation 
  assert(eOff < eOn, "Wrong controller parameters. Require eOff < eOn.");
  connect(zer.y, swi.u3);
  connect(swi.y, y);
  connect(u_m, PID.u_m);
  connect(hys.y, swi.u2);
  connect(PID.y, swi.u1);
  connect(u_s, feeBac.u1);
  connect(u_m, feeBac.u2);
  connect(feeBac.y, hys.u);
  connect(u_s, swi1.u1);
  connect(hys.y, swi1.u2);
  connect(u_m, swi1.u3);
  connect(swi1.y, PID.u_s);
end PIDHysteresis;

Buildings.Controls.Continuous.PIDHysteresisTimer

PID controller with anti-windup, hysteresis and timer to prevent short cycling

Buildings.Controls.Continuous.PIDHysteresisTimer

Information

Block of a controller for set point tracking with a hysteresis element that switches the controller on and off, and a timer that prevents the controller to short cycle.

The controller is similar to Buildings.Controls.Continuous.PIDHysteresis but in addition, it has a timer that prevents the controller from switching to on too fast. When the controller switches off, the timer starts and avoids the controller from switching on until minOffTime seconds elapsed.

Extends from Modelica.Blocks.Interfaces.SVcontrol (Single-Variable continuous controller).

Parameters

Type Name Default Description

On/off controller

Real minOffTime 600 Minimum time that devices needs to be off before it can run again

Real eOn 1 if off and control error > eOn, switch to set point tracking

Real eOff -eOn if on and control error < eOff, set y=0

Boolean pre_y_start false Value of hysteresis output at initial time

Set point tracking

SimpleController controllerType Modelica.Blocks.Types.Simple... Type of controller

Real k 1 Gain of controller

Time Ti Time constant of Integrator block [s]

Time Td Time constant of Derivative block [s]

Real yMax 1 Upper limit of modulating output

Real yMin 0.3 Lower limit of modulating output (before switch to 0)

Real wp 1 Set-point weight for Proportional block (0..1)

Real wd 0 Set-point weight for Derivative block (0..1)

Real Ni 0.9 Ni*Ti is time constant of anti-windup compensation

Real Nd 10 The higher Nd, the more ideal the derivative block

Boolean reverseAction false Set to true to enable reverse action (such as for a cooling coil controller)

Initialization

InitPID initType Modelica.Blocks.Types.InitPI... Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)

Boolean limitsAtInit true = false, if limits are ignored during initializiation

Real xi_start 0 Initial or guess value value for integrator output (= integrator state)

Real xd_start 0 Initial or guess value for state of derivative block

Real y_start 0 Initial value of output

Type	Name	Default	Description
On/off controller
Real	minOffTime	600	Minimum time that devices needs to be off before it can run again
Real	eOn	1	if off and control error > eOn, switch to set point tracking
Real	eOff	-eOn	if on and control error < eOff, set y=0
Boolean	pre_y_start	false	Value of hysteresis output at initial time
Set point tracking
SimpleController	controllerType	Modelica.Blocks.Types.Simple...	Type of controller
Real	k	1	Gain of controller
Time	Ti		Time constant of Integrator block [s]
Time	Td		Time constant of Derivative block [s]
Real	yMax	1	Upper limit of modulating output
Real	yMin	0.3	Lower limit of modulating output (before switch to 0)
Real	wp	1	Set-point weight for Proportional block (0..1)
Real	wd	0	Set-point weight for Derivative block (0..1)
Real	Ni	0.9	Ni*Ti is time constant of anti-windup compensation
Real	Nd	10	The higher Nd, the more ideal the derivative block
Boolean	reverseAction	false	Set to true to enable reverse action (such as for a cooling coil controller)
Initialization
InitPID	initType	Modelica.Blocks.Types.InitPI...	Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)
Boolean	limitsAtInit	true	= false, if limits are ignored during initializiation
Real	xi_start	0	Initial or guess value value for integrator output (= integrator state)
Real	xd_start	0	Initial or guess value for state of derivative block
Real	y_start	0	Initial value of output

Connectors

Type Name Description

input RealInput u_s Connector of setpoint input signal

input RealInput u_m Connector of measurement input signal

output RealOutput y Connector of actuator output signal

output RealOutput tOn Time since boiler switched on

output RealOutput tOff Time since boiler switched off

output BooleanOutput on Outputs true if boiler is on

Type	Name	Description
input RealInput	u_s	Connector of setpoint input signal
input RealInput	u_m	Connector of measurement input signal
output RealOutput	y	Connector of actuator output signal
output RealOutput	tOn	Time since boiler switched on
output RealOutput	tOff	Time since boiler switched off
output BooleanOutput	on	Outputs true if boiler is on

Modelica definition

model PIDHysteresisTimer 
  "PID controller with anti-windup, hysteresis and timer to prevent short cycling"
  extends Modelica.Blocks.Interfaces.SVcontrol;

  parameter Real minOffTime=600 
    "Minimum time that devices needs to be off before it can run again";
  parameter Real eOn = 1 
    "if off and control error > eOn, switch to set point tracking";
  parameter Real eOff = -eOn "if on and control error < eOff, set y=0";
  parameter Boolean pre_y_start=false 
    "Value of hysteresis output at initial time";

  parameter Modelica.Blocks.Types.SimpleController controllerType=Modelica.Blocks.Types.SimpleController.PID 
    "Type of controller";
  parameter Real k=1 "Gain of controller";
  parameter Modelica.SIunits.Time Ti "Time constant of Integrator block";
  parameter Modelica.SIunits.Time Td "Time constant of Derivative block";
  parameter Real yMax=1 "Upper limit of modulating output";
  parameter Real yMin=0.3 
    "Lower limit of modulating output (before switch to 0)";
  parameter Real wp=1 "Set-point weight for Proportional block (0..1)";
  parameter Real wd=0 "Set-point weight for Derivative block (0..1)";
  parameter Real Ni=0.9 "Ni*Ti is time constant of anti-windup compensation";
  parameter Real Nd=10 "The higher Nd, the more ideal the derivative block";
  parameter Boolean reverseAction = false 
    "Set to true to enable reverse action (such as for a cooling coil controller)";

  parameter Modelica.Blocks.Types.InitPID initType=Modelica.Blocks.Types.InitPID.DoNotUse_InitialIntegratorState 
    "Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)";
  parameter Boolean limitsAtInit=true 
    "= false, if limits are ignored during initializiation";
  parameter Real xi_start=0 
    "Initial or guess value value for integrator output (= integrator state)";
  parameter Real xd_start=0 
    "Initial or guess value for state of derivative block";
  parameter Real y_start=0 "Initial value of output";

  Modelica.Blocks.Interfaces.RealOutput tOn "Time since boiler switched on";
  Modelica.Blocks.Interfaces.RealOutput tOff "Time since boiler switched off";

  LimPID con(
    controllerType=controllerType,
    k=k,
    Ti=Ti,
    Td=Td,
    wp=wp,
    wd=wd,
    Ni=Ni,
    Nd=Nd,
    initType=initType,
    limitsAtInit=limitsAtInit,
    xi_start=xi_start,
    xd_start=xd_start,
    y_start=y_start,
    final yMin=yMin,
    final yMax=yMax,
    reverseAction=reverseAction) "Controller to track setpoint";
protected 
  Modelica.Blocks.Sources.Constant zer(k=0) "Zero signal";
  Modelica.Blocks.Logical.Switch switch2;
  Modelica.Blocks.Logical.GreaterEqualThreshold greaterEqualThreshold(threshold=
       minOffTime);
  Modelica.Blocks.Logical.And and3;
public 
  OffTimer offHys;
  Modelica.Blocks.Logical.Timer onTimer;
protected 
  Modelica.Blocks.Logical.Not not1;
public 
  Modelica.Blocks.Logical.Timer offTimer;
         Modelica.Blocks.Interfaces.BooleanOutput on 
    "Outputs true if boiler is on";
protected 
  Modelica.Blocks.Logical.Switch switch1;
public 
  Modelica.Blocks.Math.Feedback feeBac;
  Modelica.Blocks.Logical.Hysteresis hys(
    pre_y_start=pre_y_start,
    uLow=eOff,
    uHigh=eOn) "Hysteresis element to switch controller on and off";
equation 
  connect(u_m, con.u_m);
  connect(zer.y,switch2. u3);
  connect(switch2.y, y);
  connect(and3.y,switch2. u2);
  connect(greaterEqualThreshold.y, and3.u1);
  connect(offHys.y, greaterEqualThreshold.u);
  connect(con.y,switch2. u1);
  connect(onTimer.y, tOn);
  connect(offTimer.y, tOff);
  connect(and3.y, on);
  connect(and3.y, onTimer.u);
  connect(and3.y, not1.u);
  connect(not1.y, offTimer.u);
  connect(and3.y, switch1.u2);
  connect(u_s, switch1.u1);
  connect(u_m, switch1.u3);
  connect(switch1.y, con.u_s);
  connect(u_s, feeBac.u1);
  connect(u_m, feeBac.u2);
  connect(feeBac.y, hys.u);
  connect(hys.y, offHys.u);
  connect(hys.y, and3.u2);
end PIDHysteresisTimer;

Buildings.Controls.Continuous.SignalRanker

Ranks output signals such that y[i] >= y[i+1]

Buildings.Controls.Continuous.SignalRanker

Information

Block that sorts the input signal u[:] such that the output signal satisfies y[i] >= y[i+1] for all i=1, ..., nin-1.

This block may for example be used in a variable air volume flow controller to access the position of the dampers that are most open.

Extends from Modelica.Blocks.Interfaces.MIMO (Multiple Input Multiple Output continuous control block).

Parameters

Type Name Default Description

Integer nin 1 Number of inputs

Integer nout nin Number of outputs

Type	Name	Default	Description
Integer	nin	1	Number of inputs
Integer	nout	nin	Number of outputs

Connectors

Type Name Description

input RealInput u[nin] Connector of Real input signals

output RealOutput y[nout] Connector of Real output signals

Type	Name	Description
input RealInput	u[nin]	Connector of Real input signals
output RealOutput	y[nout]	Connector of Real output signals

Modelica definition

block SignalRanker "Ranks output signals such that y[i] >= y[i+1]"
   extends Modelica.Blocks.Interfaces.MIMO(final nout=nin);
protected 
  Real t "Temporary variable";
algorithm 
  y[:] := u[:];
  for i in 1:nin loop
    for j in 1:nin-1 loop
    if y[j] < y[j+1] then
      t      := y[j+1];
      y[j+1] := y[j];
      y[j]   := t;
    end if;
   end for;
  end for;
  // check algorithm (during development only)
  for i in 1:nin-1 loop
    assert(y[i] >= y[i+1], "Error in sorting algorithm.");
  end for;
end SignalRanker;

Buildings.Controls.Continuous.NumberOfRequests

Outputs the number of signals that are above/below a certain threshold

Buildings.Controls.Continuous.NumberOfRequests

Information

Block that outputs the number of inputs that exceed a threshold.

This model may be used to check how many rooms exceed a temperature threshold.

Extends from Modelica.Blocks.Interfaces.BlockIcon (Basic graphical layout of input/output block).

Parameters

Type Name Default Description

Integer nin Number of inputs

Real threShold 0 Threshold

Integer kind Set to 0 for u>threShold, to 1 for >=, to 2 for <= or to 3 for <

Type	Name	Default	Description
Integer	nin		Number of inputs
Real	threShold	0	Threshold
Integer	kind		Set to 0 for u>threShold, to 1 for >=, to 2 for <= or to 3 for <

Connectors

Type Name Description

output IntegerOutput y Number of input signals that violate the threshold

input RealInput u[nin] Input signals

Type	Name	Description
output IntegerOutput	y	Number of input signals that violate the threshold
input RealInput	u[nin]	Input signals

Modelica definition

block NumberOfRequests 
  "Outputs the number of signals that are above/below a certain threshold"
   extends Modelica.Blocks.Interfaces.BlockIcon;

  parameter Integer nin "Number of inputs";
  parameter Real threShold = 0 "Threshold";
  parameter Integer kind 
    "Set to 0 for u>threShold, to 1 for >=, to 2 for <= or to 3 for <";
  Modelica.Blocks.Interfaces.IntegerOutput y 
    "Number of input signals that violate the threshold";
  Modelica.Blocks.Interfaces.RealInput u[nin] "Input signals";
algorithm 
  y := 0;
  for i in 1:nin loop
    if kind == 0 then
      if u[i] > threShold then
        y := y+1;
      end if;
    end if;
    if kind == 1 then
      if u[i] >= threShold then
        y := y+1;
      end if;
    end if;
    if kind == 2 then
      if u[i] <= threShold then
        y := y+1;
      end if;
    end if;
    if kind == 3 then
      if u[i] < threShold then
        y := y+1;
      end if;
    end if;
  end for;
end NumberOfRequests;

Buildings.Controls.Continuous.OffTimer

Records the time since the input changed to false

Buildings.Controls.Continuous.OffTimer

Information

Block that records the time that has elapsed since its input signal switched to false.

At the beginning of the simulation, this block outputs the time that has elapsed since the start of the simulation. Afterwards, whenever its input switches to false, the timer is reset.

Extends from Modelica.Blocks.Interfaces.partialBooleanBlockIcon (Basic graphical layout of logical block).

Connectors

Type Name Description

input BooleanInput u Connector of Boolean input signal

output RealOutput y Connector of Real output signal

Type	Name	Description
input BooleanInput	u	Connector of Boolean input signal
output RealOutput	y	Connector of Real output signal

Modelica definition

model OffTimer "Records the time since the input changed to false"
  extends Modelica.Blocks.Interfaces.partialBooleanBlockIcon;

  Modelica.Blocks.Interfaces.BooleanInput u "Connector of Boolean input signal";
  Modelica.Blocks.Interfaces.RealOutput y "Connector of Real output signal";

protected 
  discrete Modelica.SIunits.Time entryTime "Time instant when u became true";
initial equation 
  pre(entryTime) = 0;
equation 
  when (not u) then
    entryTime = time;
  end when;
  y = time - entryTime;
end OffTimer;

Automatically generated Fri May 06 14:11:10 2011.