MATLAB REAL-TIME WORKSHOP EMBEDDED CODER - S Manuale Utente Scaricare il pdf (Pagina 37)

specific data information in the block untouched when running the automatic

scaling tool. Output data type and output offset are examples of block information

that can be chosen not to be effected by automatic scaling.

6.3.2 Real-Time Workshop Embedded Coder

To support fixed-point implementations, Matlab must have the Fixed-Point

Toolbox installed as well as RTW EC. Fixed-point is supported in many useful

blocks, see Appendix III. By knowing which blocks that support fixed-point, the

user can build the desired model without any problem. Any control model can be

build if the supported blocks are used wisely. The Matlab Fixed-Point Toolbox

supports both power of two scaling and arbitrary scaling.

In RTW EC automatic scaling is supported depending on simulation results

ranges. No worst case range propagation is supported in Real-Time Workshop

Embedded Coder/ Simulink Fixed-Point Toolbox. Propagations depending on the

simulation ranges are not preferred. To obtain a useful result the user has to

choose the simulation inputs very carefully to cover all the critical ranges.

Another problem is that the user cannot have fixed outputs ranges after automatic

scaling. The automatic scaling tool propagates ranges depending on the simulation

inputs, the outputs of the model will then have specific ranges which are

determined by the scaling tool. This results in output scaling factors that do not

match those required by the company.

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MATLAB REAL-TIME WORKSHOP EMBEDDED CODER - S Manuale Utente Pagina 37