stateflow 변수 초기화 방법

stateflow에서 위와 같이 모델링 할경우 아래와 같이 a 초기값을 선언해달라고 하는데.

c언어에서 처럼 static a=0 과 같이 local 변수지만 초기화만 할수 있는 방법이 없을까요?

state에서는 en : a=0으로 할수는 있을거 같은데

많이 사용하는 방법에 대해 문의 드립니다.

The data a was read before being written to. This error will stop the simulation. Transition in Chart 'untitled/Chart': [a < 9]

[Walter Roberson]

It looks like you are trying to read a in the condition [a < 9] before a has been assigned a value.

[영진]

In stateflow, when modeling as above, it asks to declare the initial value of a as below.

Is there no way to initialize it as a local variable like static a=0 in C language?

I think it is possible to do en: a=0 in state,

but I am asking about a method that is commonly used.

[Walter Roberson]

According to https://www.mathworks.com/matlabcentral/answers/838503-persistent-data-in-stateflow#answer_708430

Variables you define as 'local' or as 'output' in the chart are persistent over chart executions.

Answer 1

[Shivam Gothi]

Hello @영진,

As per my understanding, you are trying to implement the logic that is similar to “static a=0” in C language.

I was not able to reproduce the issue faced by you, but it seems that you are trying to implement the below logic:

1. Initialise variable “a” with 0.
2. If “a<9”, then increment “a” and set “y=1”
3. Keep on iterating step-2 untill the condition “a<9” holds true.
4. When “a” becomes greater than or equal to 9, then make the variables “a=0” and “y=0”

To implement above logic using Simulink “Chart”, I made a small change in your flowchart model as shown below:

I have added a “State” block and attached the “default transition” with it. Inside the “state” block, I initialised the variable “a” with value of “0”

In the “symbols pane” (found under “modelling” tab), I selected the “Type” of variable “a” as “local” and the “Type” of variable “y” as “Output”. This created an output port as shown below.

Now, you can observe the value of variable “y” on scope as shown below.

Conclusion:

As long as the condition 'a < 9' holds true, the variable 'a' continues to increment, while 'y' remains set at the value of 1. Once the condition 'a < 9' is no longer met, both variables are reset, with 'a' returning to 0 and 'y' also resetting to 0.

(Note: Here, I configured the “sampling time” of the block “state” to “0.01” from its “block parameters”)

I have also attached the Simulink model with this answer.

I hope it helps!

[영진]

Thank you so much.