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1 Getting Started

1.1 FMI Code Generation Steps

This chapter describes how to use the FMI app and in the Example: RLC Circuit Model section of this chapter, a step by step procedural example shows you how to create an FMU archive file.  The FMU Generation app consists of the following steps to generate C code:

1. 

Subsystem selection

2. 

Inputs/Outputs and parameter management

3. 

FMI code generation options

4. 

Generate FMI C code

5. 

View generated FMI C code

The FMI Connector package

The FMI Connector package is a collection of procedures for manually generating and compiling FMI code from MapleSim models.  For information about the FMI Connector package, in Maple, refer to the FMIConnector help page.

1.2 Opening an FMI app

To open the FMU Generation app

1. 

Select the Add Apps or Templates tab ( ).

2. 

Double-click the FMU Generation entry in the Apps palette. The Analysis window opens with FMU Component Code Generation app loaded in the Apps tab.

3. 

In the Subsystem Selection section, select a subsystem from the drop down list.

1.3 Using the FMU Generation App

The MapleSim FMI Connector provides an FMU Generation app for manipulating and exporting MapleSim subsystems as FMU archive files.

With this app, you can define inputs and outputs for the system, set the level of code optimization, generate the source code, and choose the format of the resulting FMU component and library code.  You can assign model equations to a variable, group inputs and outputs, and define additional input and output ports for variables.

Note: FMU component generation now handles all systems modeled in MapleSim, including hybrid systems with defined signal input (RealInput) and signal output (RealOutput) ports.

Example models are available in MapleSim. To access these, from the Help menu, select Examples > FMI Connector Examples.

Step 1: Subsystem Selection

This part of the app identifies the subsystem modeling components that you want to export as a block component.

To connect a subsystem to modeling components outside of its boundary, you add subsystem ports to your model. A subsystem port is an extension of a component port in your subsystem. The resulting signals can then be directed as inputs and outputs for the FMU archive files. By creating a subsystem you improve the visual layout of a system in the model workspace and also prepare the model for export.  The example in Chapter 2 shows you how to group all of the components into a subsystem.

You can select  which subsystems from your model you want to export to an FMU archive file.  After selecting a subsystem, click Load Selected Subsystem.  All defined input and output ports are loaded.

Step 2: Inputs, Outputs, and Parameters

The Inputs, Outputs, and Parameters sections let you customize, define, and assign parameter values to specific ports. Subsystem components to which you assign the parameter inherit a parameter value defined at the subsystem level.

After the subsystem is loaded you can group individual input and output variable elements into a vector array, and add additional input and output ports for customized parameter values. Input ports can include variable derivatives, and output ports can include subsystem state variables. You can specify prefixes for both input and output port variables. The prefix for the input (output) port variables will be applied to all the variables in the input ports (outputs) table.

 

 

 

 

 

Note:  If the parameters are not marked for export they will be numerically substituted. Parameters marked as tunable will also be marked for export by default. However, tunable parameters will be ignored if FMI Version and Environment (see Step 3: Export Options) are anything other than FMI 2.0 and Co-Simulation. To use fully qualified parameter names for the generated FMU, check the corresponding check box; otherwise, short parameter names will be used by default.

Step 3: Export Options

Select Export Options to specify the advanced options for the code generation process.  Default settings are provided for both Model Exchange and Co-Simulation export options.

FMI Version and Environment

Select the FMI version and environment for your code. You can choose between FMI 1.0 and FMI 2.0 for the version, and between Model Exchange and Co-Simulation for the environment.

Select View advanced FMU settings to see Contraint Handling, Event Handling, and Code Generation options.

To match the MapleSim model's current simulation settings, click the Match Simulation Settings button. (Note that you can revert to the default settings for Model Exchange and Co-Simulation using the refresh button  at the top of the app window.)

Cosimulation Solver Settings

For cosimulation, the Co-Simulation Solver can be set to Euler, RK2, RK3, RK4, Implicit Euler, CK45, or Rosenbrock.  The communication step size can also be specified.

 

Specify Solver Options for the chosen solver.

Jacobian: In the case of the Implicit Euler solver, specify either numeric or symbolic formulation for the system Jacobian.

Advanced FMU Settings

 

The Constraint Handling Options specifies whether the constraints are satisfied in a DAE system by using constraint projection in the generated FMU archive file. Use this option to improve the accuracy of a DAE system that has constraints. If the constraint is not satisfied, the system result may deviate from the actual solution and could lead to an increase in error at an exponential rate.

The Baumgarte constraint stabilization method stabilizes the position constraint equations, by combining the position, velocity, and acceleration constraints into a single expression. By integrating the linear equation in terms of the acceleration, the Baumgarte parameters, alpha and beta, act to stabilize the constraints at the position level.

 

Baumgarte stabilization: Apply the Baumgarte constraint stabilization.

Alpha: Set the derivative gain for Baumgarte constraint stabilization.

Beta: Set the proportional gain for Baumgarte constraint stabilization.

Set the Projection iterations to specify the maximum number of times that a projection is permitted to iterate to obtain a more accurate solution.

Set the Projection tolerance to specify the desirable error tolerance to achieve after the projection.

 

The Event Handling Options specifies whether the events are satisfied in a DAE system by using event projection in the generated FMU archive file.  Use this option to improve the accuracy of a DAE system with events. If the constraint is not satisfied, the system result may deviate from the actual solution and could lead to an increase in error at an exponential rate.

Set the Event iterations to specify the maximum number of times that a projection is permitted to iterate to obtain a more accurate solution.

Set the Initial hysteresis to specify the desirable error tolerance to achieve after the projection.

Select Event projection to perform event projection using the event projection routine in the External Model Interface as described on The MathWorks web site to control the drift in the result of the DAE system.

Note: Currently, if the model has events, they are handled using the event handling functions in the generated MsimModel.c file, and not the FMI provided Event Handling routines.

 

The Code Generation Options control details of the generated code and run-time errors.

Add directional derivatives: Select the check box to generate directional derivatives code.

Optimize for fixed-step solver: Specifies if the generated code should be optimized for use with fixed-step solvers.

Detailed run-time errors: Report run-time errors in detail.

Add extended variables: Choose between minimal and extended variable tracking during the simulation.

Step 4: Info Options

In the generated FMU archive file, model information (for example, variable names, units and initial values) are stored in a text file in XML format. Additional information about the model, such as the model author, description, and version, can also be included in this file.

 

Author: Name and organization of the model author (for example, J. Smith, Maplesoft http://www.maplesoft.com).

Description: Brief description of the model (for example, Model of a lithium-ion battery).

Version: Model version or FMU version.

Copyright: Intellectual property copyright (for example, (C) Maplesoft 2019).

License: Intellectual property licensing (for example, Proprietary, Public Domain, or BSD License).

 

Step 5: Export

Generating the C code creates temporary files for viewing purposes.

Specify the locations for the Target Directory and Visual C++ Directory.

Note:  The Visual C++ Directory is not required for Linux and Mac® platforms. For Windows platforms, a typical location for the Visual C++ Directory is: C:\Program Files (x86)\Microsoft Visual Studio\version\WDExpress\VC (64-bit) or C:\Program Files\Microsoft Visual Studio version\VC (32-bit). If necessary, navigate to the correct Visual C++ Directory for your platform using the Browse button.

Provide a name for the generated FMU archive in FMU Archive Name.

If required, set the binary target to 32-bit or 64-bit.

Select Remove Source Files from the FMU Archive: to remove source files after code generation.

Select Remove temporary `fmiTMPXXXXXX`directory to remove temporary files after code generation.

To generate an FMU archive click Generate FMU Archive.

Note: If your model contains an external library, you must add the directory that contains the external library to your search path. See Adding External Libraries to Your Search Path for instructions on how to do this.

Step 6: View Code

After the C code is generated, the FMI C Code and MsimModel.c components can be viewed.

1.4 Enabling Extended Visualization Data

You can enable the generation of extended visualization data in your FMU. Extended visualization data is used to produce FMU simulation results (that is, plots and 3-D animations) that can be imported back into MapleSim. To do this, you need to set two parameters in the FMU generated by the MapleSim FMI Connector using a third-party FMU tool that allows you to view and edit parameters.

To enable extended visualization data, set the following FMU parameters:

• 

binfilename: Enter a file name with a .bin file extension for the extended visualization data file. The extended visualization data file is necessary in order to import the FMU simulation results into MapleSim. Enter DISABLED if you do not want to generate extended visualization data.

• 

minsamplestep: Enter the minimum sample step, in seconds, for the extended visualization data in the .bin file. The default value is 2.5e-2 s (that is 1/40 of a second). This sample step is used for both plots and 3-D animations (for 3-D models). For example, a sample step of 1/40 of a second generates plot points every 1/40 of a second and gives you a frame rate of 40 frames per second in your 3-D animation. Smaller values for the minimum step size give smoother plots and animations, but result in much larger .bin files.

After you execute your FMU, the extended visualization data file is created in the same directory that your FMU is in. See MapleSim > Using MapleSim > Simulating a Model > Importing FMU or Simulink(R) S-function Results in the MapleSim help system for information on how to import these results into MapleSim.

1.5 Viewing Examples

Within MapleSim there are many examples for you to view.

To view an example:

1. 

From the Help menu, select the Examples > FMI Connector Examples menu, and then click the entry for the model that you want to view.

Note: Some models include additional documents, such as templates that display model equations or define custom components.

2. 

In the Attached Files tab, expand Documents.  You can open any of these documents by right-clicking (Control-clicking for Mac) its entry in the list and clicking View.  After you add a template to a model, it will be available from this list.

1.6 Example: RLC Circuit Model

In this example, you will generate an FMU archive file using an RLC circuit model created in MapleSim.

To generate an FMU archive file:

1. 

From the Help menu, select Examples > FMI Connector Examples, and then select the RLC Parallel Circuit example.

2. 

Select the Add Apps or Templates tab ( ).

3. 

Double-click on the FMU Generation entry in the Apps palette. The Analysis window opens with the FMU Component Code Generation app loaded in the Apps tab.

4. 

Select the RLC subsystem from the drop-down list in the Subsystem Selection section. This menu displays all of the subsystems and components in your MapleSim model.

5. 

Click Load Selected Subsystem.  All of the app fields are populated with information specific to the subsystem displayed in the model diagram.  You can now specify which subsystem parameters will be kept as configurable parameters in the generated block.

6. 

In the Export section of the app, specify the target directory, the Visual C++ directory, and the FMU archive name.

7. 

Click Generate FMU Archive.  The .fmu zip file is created and saved in the target directory.

Note: Generating a block may require a few minutes.

 

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