Opentheex_units_fuelsysexample model.

For the top model, theAllowed unit systemsconfiguration parameter determines the unit systems the model can use. For each of the plant and controller subsystems, aUnit System Configurationblock determines the allowed unit systems.

In the plant subsystem, on theSignal Attributestab of eachInportblock dialog box, set theUnitparameter to a value appropriate for the connected physical signal.

To display units on ports and signals in the model, on theDebugtab, selectInformation Overlays>Port Units.

In the plant subsystem, you see units on theInport块和连接符号als.

Navigate back to the top model. To compile the model, pressCtrl+D, which also performs unit consistency checking.

The model displays a warning to indicate that there is a disallowed unit for thethrottle anglesignal. Clicking the warning icon displays a link to a Model Advisor report that gives you more detail.

The model also displays the warning at the bottom of the model editing window.

In the plant subsystem, you specified a unit of度(degrees) for thethrottle anglesignal. However, the warning message indicates that degrees are not in the SI unit system. As determined by theAllowed unit systemsconfiguration parameter,SIis the only unit system that the top model currently allows. To resolve this warning, you have two options:

In this case, a unit of度for thethrottle anglesignal is appropriate. Instead, to resolve the warning, expand the set of allowed unit systems for the top model. Set theAllowed unit systemsconfiguration parameter of the top model toall. To recompile the model, pressCtrl+D.

The top model no longer displays warnings.

Now that you have introduced units to the plant and successfully resolved unit inconsistency problems, you can add units to the controller. In theFuel Rate Controllersubsystem, set theUnitparameter of thefuel_rateOutportblock tokg/s(kilograms per second).

Navigate back to the top model. To recompile it, pressCtrl+D.

The top model now shows a warning for mismatched units between the controller and plant. To resolve this error, you can:

Both options convert units in the same way. A situation in which you might disallow automatic conversions and insert conversion blocks instead is when you are integrating many components in a large system model. In that case, manually inserting conversion blocks can give you an added degree of control of unit conversions in the model. Also, with a conversion block, you can control the data type of the converted signal. This is useful, for instance, when you are modeling for fixed-point precision.

In this case, to enable Simulink^®to resolve the unit mismatch automatically, selectAllow automatic unit conversions. To recompile the model, pressCtrl+D.

Simulink automatically converts units between the controller and the plant. An automatic conversion icon replaces the warning.

The top model includes aSimulink.Busobject namedEngSensorsthat passes various sensor signals as a composite signal to the controller. To use the Bus Editor to add units to individual elements of the bus object, on theModelingtab, underDesign, clickBus Editor. Then, specify the units in the table or in theProperty Inspectorpane.

For theEngSensorsbus object, set theUnitparameter of each element.

To recompile the model, pressCtrl+D.

The model shows units on the individual elements of the bus object.

You can also see the units in the interface view of your model. On theModelingtab, underDesign, clickModel Interface.

Theairflow_calcblock of the controller subsystem displays units on the individual elements of the bus object, both at the component interface and within the component.

After you introduce units incrementally and resolve inconsistency and mismatch issues, you can simulate the model.

For thefuelsignal that is connected to the scope, the plot window displays the associated units ofkg/sas ay-axis label.