10 Model Advisor Checks

Check for proper bus usage

Identify Mux blocks used as a bus creator and bus signal that Simulink treats as a vector.

Description

Models should not contain bus signals that Simulink software implicitly converts to vectors. Instead, either insert a Bus to Vector conversion block between the bus signal and the block input port that it feeds, or use the

Simulink.BlockDiagram.addBusToVector command.

Results and Recommended Actions

Action Results

Clicking Modify causes one of the following:

•Mux blocks are replaced by Bus Creator blocks.

•Bus to Vector blocks are inserted at the inports of blocks that implicitly convert bus signals to vectors.

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Simulink® Checks

Tips

•The Bus to Vector conversion block resides in the Simulink/Signal Attributes library.

•Run this check before running Check consistency of initialization parameters for Outport and Merge blocks.

•The “Non-bus signals treated as bus signals” diagnostic detects when Simulink implicitly converts a non-bus signal to a bus signal to support connecting the signal to a Bus Assignment or Bus Selector block.

This diagnostic is in the Configuration Parameters dialog box, on the

Diagnostics> Connectivity pane.

•Using a Mux block to create a virtual bus does not support strong type checking and increases the likelihood of run-time errors. In new applications, do not use Mux blocks to create bus signals. Consider upgrading existing applications to that use of Mux blocks.

-Simulink generates a warning when you load a model created in a release prior to R2010a, if that model contains a Mux block to create a bus signal. For new models, Simulink generates an error.

See Also

•“Avoid Mux/Bus Mixtures”

•Bus to Vector block

•“Mux blocks used to create bus signals”

•“Bus signal treated as vector”

•“Check consistency of initialization parameters for Outport and Merge blocks” on page 10-37

•Simulink.BlockDiagram.addBusToVector

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10 Model Advisor Checks

Check for potentially delayed function-call subsystem return values

Identify function-call return values that might be delayed because Simulink software inserted an implicit Signal Conversion block.

Description

So that signals reside in contiguous memory, Simulink software can automatically insert an implicit Signal Conversion block in front of function-call initiator block input ports. This can result in a one-step delay in returning signal values from calling function-call subsystems. The delay can be avoided by ensuring the signal originates from a signal block within the function-call system. Or, if the delay is acceptable, insert a Unit Delay block in front of the affected input ports.

Results and Recommended Actions

See Also

Signal Conversion block

Unit Delay block

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Simulink® Checks

Identify block output signals with continuous sample time and non-floating point data type

Find continuous sample time, non-floating-point output signals.

Description

Non-floating-point signals might not represent continuous variables without loss of information.

Results and Recommended Actions

See Also

“What Is Sample Time?”.

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