Fixed-Point Blockset

2. Data Type Override

You can obtain ideal simulation limits by using the automatic scaling tool. However, you must first perform a data type override with doubles of all blocks with fixed-point output, and you must log maximum and minimum simulation values for all blocks that are to be scaled.

1. Make sure the Logging Mode parameter is set to Min, max and overflow for the fxpdemo_feedback system. This overrides all local logging settings for the subsystems of the model.
2. Perform a data type override with doubles by setting the Data type override parameter in the interface to True Doubles. This overrides all local data type settings for the subsystems of the model.
3. Run the simulation by clicking the Run button.
4. Click the Plot button to launch the Plot System interface.
5. Compare the ideal (doubles) and fixed-point plant output signals using the Plot System interface.

The ideal and fixed-point plant output signals are shown below. The ideal signal is produced by overriding the block output scaling with true doubles.

1. Initial Guess at Scaling

3. Automatic Scaling