Class fmipp.VariableStepSizeFMU

class VariableStepSizeFMU(fmuDirUri, modelIdentifier[, loggingOn=False, timeDiffResolution=1e-4])

This class eases the use of FMUs for Co-Simulation in case variable communication step sizes are supported by the FMU. Its handling is very similar to class IncrementalFMU, i.e., it defines the methods defineRealInputs(...), defineRealOutputs(...), getRealOutputs(...), etc. in an analogous way.

Note

This class uses objects of type SwigPyObject as inputs and outputs, which are wrappers around C/C++ arrays. Instantiation of and data access to these objects should be done via the corresponding helper functions.

Parameters

  • fmuDirUri (str) – URI to the unzipped FMU

  • modelIdentifier (str) – model identifier of the FMU

  • loggingOn (bool) – enable logger for debugging

  • timeDiffResolution (float) – internal resolution for comparing time differences

Methods for interacting with the FMU

init(instanceName, realVariableNames, realValues, nRealVars, [integerVariableNames, integerValues, nIntegerVars, booleanVariableNames, booleanValues, nBooleanVars, stringVariableNames, stringValues, nStringVars, ]startTime, defaultCommunicationStepSize[, stopTimeDefined=False, stopTime=float('inf'), timeout=0, visible=False, interactive=False])

Initialize the internal FMU model.

Parameters

  • instanceName (str) – a unique identifier for a given FMI component instance, used to identify a component within a co-simulation graph model and for logging messages

  • realVariableNames (SwigPyObject) – names of real variables

  • realValues (SwigPyObject) – initial values of real variables

  • nRealVars (int) – number of real variables to be initialized

  • integerVariableNames (SwigPyObject) – names of integer variables

  • integerValues (SwigPyObject) – initial values of integer variables

  • nIntegerVars (int) – number of integer variables to be initialized

  • booleanVariableNames (SwigPyObject) – names of boolean variables

  • booleanValues (SwigPyObject) – initial values of boolean variables

  • nBooleanVars (int) – number of boolean variables to be initialized

  • stringVariableNames (SwigPyObject) – names of string variables

  • stringValues (SwigPyObject) – initial values of string variables

  • nStringVars (int) – number of string variables to be initialized

  • startTime (float) – can be used together with stopTime to check whether the model is valid within the given boundaries or to allocate memory which is necessary for storing results

  • defaultCommunicationStepSize (float) – default communication step size

  • stopTimeDefined (bool) – if True, the FMU returns statusError if the environment tries to compute past stopTime.

  • stopTime (float) – can be used together with startTime to check whether the model is valid within the given boundaries or to allocate memory which is necessary for storing results

  • timeout (float) – a communication timeout value in milli-seconds to allow interprocess communication to take place (a value of 0 indicates an infinite wait period)

  • visible (bool) – indicates whether or not the simulator application window needed to execute a model should be visible (False indicates that the simulator is executed in batch mode, True indicates that the simulator is executed in interactive mode)

  • interactive (bool) – indicates whether the simulator application must be manually started by the user (False indicates that the co-simulation tool automatically starts the simulator application and executes the model referenced in the model description, True indicates that the simulator application must be manually started by the user)

Return type

int

Returns

1 on success, 0 on failure

sync(t0, t1[, realInputs, integerInputs, booleanInputs, stringInputs, iterateOnce=False])

Simulate FMU from time t0 until t1. If provided, the inputs are set at the end of the interval [t0, t1]. Method sync(...) always returns the time of the next FMU communication point. Whenever an FMU communication point is reached, the latest inputs are handed to the FMU. This means, that multiple calls to sync(...) between two FMU communication points with different inputs will only cause the latest input to be handed to the FMU (no queueing).

Parameters

  • t0 (float) – simulation interval start time

  • t1 (float) – simulation interval end time

  • realInputs (SwigPyObject) – real inputs, previously defined via defineRealInputs(...)

  • integerInputs (SwigPyObject) – integer inputs, previously defined via defineIntegerInputs(...)

  • booleanInputs (SwigPyObject) – boolean inputs, previously defined via defineBooleanInputs(...)

  • stringInputs (SwigPyObject) – string inputs, previously defined via defineStringInputs(...)

  • iterateOnce (bool) – if True, iterate the FMU (simulation step with length 0) at time t1

Return type

float

Returns

time of the next FMU communication point

iterateOnce()

Iterate the FMU (simulation step with length 0).

Methods for defining inputs/outputs

defineBooleanInputs(inputs, nInputs)

Define boolean inputs to be applied to the FMU via the sync(...) method.

Parameters

  • inputs (SwigPyObject) – initial values of the input variables

  • nInputs (int) – number of boolean inputs

defineBooleanOutputs(outputs, nOutputs)

Define boolean outputs to be retrieved from the FMU via the getBooleanOutputs(...) method.

Parameters

  • outputs (SwigPyObject) – initial values of the output variables

  • nOutputs (int) – number of boolean outputs

defineIntegerInputs(inputs, nInputs)

Define integer inputs to be applied to the FMU via the sync(...) method.

Parameters

  • inputs (SwigPyObject) – initial values of the input variables

  • nInputs (int) – number of integer inputs

defineIntegerOutputs(outputs, nOutputs)

Define integer outputs to be retrieved from the FMU via the getIntegerOutputs(...) method.

Parameters

  • outputs (SwigPyObject) – initial values of the output variables

  • nOutputs (int) – number of integer outputs

defineRealInputs(inputs, nInputs)

Define real inputs to be applied to the FMU via the sync(...) method.

Parameters

  • inputs (SwigPyObject) – initial values of the input variables

  • nInputs (int) – number of real inputs

defineRealOutputs(outputs, nOutputs)

Define real outputs to be retrieved from the FMU via the getRealOutputs(...) method.

Parameters

  • outputs (SwigPyObject) – initial values of the output variables

  • nOutputs (int) – number of real outputs

defineStringInputs(inputs, nInputs)

Define string inputs to be applied to the FMU via the sync(...) method.

Parameters

  • inputs (SwigPyObject) – initial values of the input variables

  • nInputs (int) – number of string inputs

defineStringOutputs(outputs, nOutputs)

Define string outputs to be retrieved from the FMU via the getStringOutputs(...) method.

Parameters

  • outputs (SwigPyObject) – initial values of the output variables

  • nOutputs (int) – number of string outputs

Methods for getting variable values

getBooleanOutputs()
Return type

SwigPyObject

Returns

value of boolean outputs

getIntegerOutputs()
Return type

SwigPyObject

Returns

value of integer outputs

getRealOutputs()
Return type

SwigPyObject

Returns

value of real outputs

getStringOutputs()
Return type

SwigPyObject

Returns

value of string outputs

Miscellaneous methods

getLastStatus()
Returns

status returned by latest internal FMU function call

Return type

int (statusOK, statusWarning, statusDiscard, statusError or statusFatal)