Chapter 14  Preparing Models for
Use with Reactis

To use Reactis on a Simulink / Stateflow model, a user must ensure that the model satisfies certain constraints. This chapter describes what these constraints are. Please note that, while every effort is made to maintain the accuracy of the following list of supported and unsupported features, due to the complexity and continual evolution of the Simulink / Stateflow notation this description may not be complete. For example, some blocks listed as supported do not support all parameters for the block. A block or feature not listed as either supported or unsupported should be assumed to be unsupported.

We encourage all potential customers to take advantage of a free evaluation license for Reactis to determine if the subset of Simulink / Stateflow supported by Reactis is adequate for your models. If not, please let us know what features or blocks are lacking. Reactive Systems uses such feedback to prioritize enhancements to Reactis.

14.1  MATLAB

Reactis can process Simulink / Stateflow models that contain embedded MATLAB , provided that certain conventions are observed. On the one hand, files that define workspace data items referred to in a model must be “connected” to the model appropriately, and certain MATLAB functions should be avoided. The remainder of this section elaborates on these points.

14.1.1  Workspace Data Items

Reactis invokes MATLAB to evaluate many MATLAB expressions, but it does not directly interact with an executing MATLAB session in the same way that Simulink does. For this reason, any workspace data items that a model uses must be included in .m files that are attached to a model using Simulink's pre-load callback. For the cruise-control example, the file cruise_constants.m defines two workspace variables that are used in cruise.mdl. One attaches cruise_constants.m to cruise.mdl as follows:

1. Load cruise.mdl into Simulink.
2. From the Simulink window, select the File -> Model Properties menu item.
3. In the resulting dialog, select the Callbacks tab.
4. In the Model pre-load function entry box enter cruise_constants.
5. Save the model.

In general, using the pre-load callback in this manner is good modeling practice, since once the .m files are attached to a model file, loading the model file into Simulink (and not just Reactis) will automatically load the .m files as well.

14.1.2  Unsupported MATLAB Features

While Reactis supports most of MATLAB , the following exceptions may not be used in Simulink / Stateflow models, e.g. in callbacks or mask initializations.

14.2  Simulink

Reactis currently supports versions 4.x, 5.x, 6.x and 7.x of Simulink (MathWorks releases R12, R13, R14, R2006a, R2006b, R2007a, R2007b). Most features of Simulink are supported. Some notable exceptions are:

• Simulink signals with more than 2 dimensions are not supported.
• Reactis does not support the use of complex values (i.e. values with real and imaginary parts) in Simulink signals
• Models must not contain corresponding DataStoreWrite/DataStoreRead blocks whose execution order is not explicitly defined by either the model logic or priorities.

For the subset of Simulink blocks supported by Reactis please refer to section 14.2.2 and below. For blocks that can be either continuous- or discrete-time, only the discrete-time version is supported. Blocks marked by a “*” are not natively supported by Reactis but are available in the Reactis block library.

14.2.1  S-Functions

Reactis supports both C-Coded and M-File S-functions, with some restrictions. For C-Coded S-functions, the following are not supported by Reactis:

• Port-based sample times.
• Multiple sample times.
• Complex number signals.
• Zero-crossing detection.
• Output of function-calls.
• Level 1 S-functions (For a guide on how to convert Level 1 S-functions to Level 2 S-functions — which are supported by Reactis - please consult the Simulink user's guide)
• Calling any function from MATLAB's “mex” library (including mexCallMATLAB, mexEvalString and mexGetVariable) from an S-Function.

For M-File S-functions, the following are not supported by Reactis:

• Multiple sample times.
• Complex number signals.
• Level 2 S-functions.

In addition to the above restrictions, care must be taken about any internal data that is stored by S-functions. In order to work properly, Reactis must be able to retrieve and reset the values of all internal states of any S-function occurring within a model. The best way to make internal states visible to Reactis (and Simulink) is to declare the appropriate number of discrete states in the mdlInitializeSizes() function and then use the state vector that Reactis and Simulink will provide. Reactis will also save and restore memory that an S-function allocates as a result of calling the ssGetNumRWork() and ssGetNumIWork() during mdlInitializeSizes.

Reactis has no way of knowing about any other persistent data that an S-function maintains by other means, such as:

• global or static variables in C-code;
• memory allocated by malloc() or mxMalloc() functions in C-code;
• Use of workspace variables in M-File S-functions.

Reactis will also not save and restore memory requested by ssGetNumPWork(), since otherwise pointers stored in this vector by your S-function might get lost or mangled, resulting in memory leaks or crashes.

If an S-function stores internal states in any of the unsupported ways described above, Reactis will seem to work properly, but the test suites generated by Tester may include wrong outputs. One sign of this can be if you run a test suite in Simulator and get an error message saying “Model fails test”. Another problem of such invalid use of internal states may be invalid outputs after using the “back” buttons in Simulator.

14.2.2  MathWorks R12

14.2.3  MathWorks R13

14.2.4  MathWorks R14, R2006a, R2006b

14.2.5  R2007a

14.2.6  R2007b

14.3  Stateflow

Reactis supports all of Stateflow, except for the following:

• Implicit “enter”, “exit” and “change” events
• Range limits for variables.
• “ml.” namespace operator and “ml()” function call.
• Embedded Matlab code.
• When using expressions in the 'size' field of a Stateflow variable declaration, all references to constants within the expression must refer to constants that are defined in the MATLAB workspace.
• Using Stateflow keywords as variable names. The Stateflow keywords are: at, after, before, change, du, during, enter, en, entry, every, ex, exit, in, on, ml, send, abs, acos, asin, atan, atan2, ceil, cos, cosh, exp, fabs, floor, fmod, labs, ldexp, log, log10, min, max, pow, rand, rem, sin, sinh, sqrt, tan, tanh, int8, int16, int32, uint8, uint16, uint32, double, boolean.
• Charts with no trigger or sample time.
• In some cases, the detection of inner transitions fails for odd-shaped transitions (for example, single transition segments which leave and reenter a state).
• Directly accessing Simulink Datastore blocks.
• Using “bind” actions.