Debug Run-Time Errors in a State Transition Table
A state transition table represents a finite state machine for sequential modal logic in tabular format. Instead of drawing states and transitions in a Stateflow® chart, you can use a state transition table to model a state machine in a concise, compact format that requires minimal maintenance of graphical objects. For more information, see State Transition Tables in Stateflow.
Create the Model and the State Transition Table
Create a Simulink® model with a new State Transition Table.
Add the following states and transitions to your table:
The table has two states at the highest level in the hierarchy,
Power_on. By default,
Power_offis active. The event
SWITCHtoggles the system between the
Power_onhas three substates:
Third. By default, when
Firstalso becomes active. When
Shiftequals 1, the system transitions from
First, for each occurrence of the event
SWITCH. Then the pattern repeats.
Add two inputs from Simulink:
An event called
SWITCHwith a scope of Input from Simulink and a Rising edge trigger.
A data called
Shiftwith a scope of Input from Simulink.
In the model view, connect a Sine Wave block as the
SWITCHevent and a Step block as the
Shiftdata for your State Transition Table.
In the model, there is an event input and a data input. A Sine Wave block generates a repeating input event that corresponds with the Stateflow event
SWITCH. The Step block generates a repeating pattern of 1 and 0 that corresponds with the Stateflow data object
Shift. Ideally, the
SWITCHevent occurs at a frequency that allows at least one cycle through
Debug the State Transition Table
To debug the table in Create the Model and the State Transition Table, follow these steps:
Power_offstate, and select Set Breakpoint > On State Entry.
Start the simulation.
Because you specified a breakpoint on
Power_off, execution stops at that point.
Move to the next step by clicking the Step In button, .
To see the data used and the current values, hover your cursor over the different table cells.
Continue clicking the Step In button and watching the animating states. After each step, watch the chart animation to see the sequence of execution. Use the tooltips to see the data values.
Single-stepping shows that the loop from
Third inside the state
Power_on does not occur. The transition from
Correct the Run-Time Error
In Debug the State Transition Table, you step through a simulation of a
state transition table and find an error. The event
the simulation, but the simulation time passes too quickly for the input data object
Shift to have an effect.
To correct this error:
Stop the simulation so that you can edit the table.
Add the condition
after(20.0, sec)to the transition from
Now the transition from
Power_offdoes not occur until 20 seconds have passed.
Click the Step In button repeatedly to observe the fixed behavior.