你如何控制執行不同的ST代碼塊的順序？

Question

我有8個步驟的過程配方，每個步驟都在ST中定義。然而，用戶應該能夠選擇執行這8個步驟的順序。我試圖想出可用於此的標誌或變量，但迄今爲止繪製了一個空白。有沒有人有任何想法如何實現這一點？

Answer 1

我的建議是讓用戶按照應該如何執行的順序填充步驟編號。然後將您的不同S​​T代碼塊放入CASE語句中。對於CASE變量，使用數組。這樣執行的順序就非常靈活。

這裏是一個三明治裝飾作爲例子。最重要的部分開始於E_SandwichDecoratorStep.RecipeExecution

枚舉：

TYPE E_SandwichDecoratorStep : 
(
    UserSelecting := 1, 
    RecipeExecution, 
    Finished 
); 
END_TYPE 

---

TYPE E_SandwichDecoratorUserRecipe : 
(
    Pepperoni := 1, 
    Ham, 
    Cheese, 
    Tomato, 
    Salad, 
    Sauce, 
    Salt, 
    Pepper 
); 
END_TYPE 

計劃：

PROGRAM SANDWICHDECORATOR 
VAR 
    arrnStepOrder  : ARRAY[1..8] OF E_SandwichDecoratorStep; (*User Recipe Configuration*) 

    bRestart   : BOOL; 
    bUserRecipeStart : BOOL; (*Start the execution of the Recipe*) 
    eCurStep   : E_SandwichDecoratorStep; 
    nCurUserRecipeIndex : INT := 1; 
END_VAR 

---

CASE eCurStep OF 
    E_SandwichDecoratorStep.UserSelecting: 
     (*Example Order*) 
     arrnStepOrder[1] := E_SandwichDecoratorUserRecipe.Ham; 
     arrnStepOrder[2] := E_SandwichDecoratorUserRecipe.Tomato; 
     arrnStepOrder[3] := E_SandwichDecoratorUserRecipe.Pepperoni; 
     arrnStepOrder[4] := E_SandwichDecoratorUserRecipe.Cheese; 
     arrnStepOrder[5] := E_SandwichDecoratorUserRecipe.Salt; 
     arrnStepOrder[6] := E_SandwichDecoratorUserRecipe.Sauce; 
     arrnStepOrder[7] := E_SandwichDecoratorUserRecipe.Pepper; 
     arrnStepOrder[8] := E_SandwichDecoratorUserRecipe.Salad; 

     IF bUserRecipeStart THEN 
      bUserRecipeStart := FALSE; 
      eCurStep := E_SandwichDecoratorStep.RecipeExecution; 
     END_IF 

    E_SandwichDecoratorStep.RecipeExecution: 
     IF nCurUserRecipeIndex <= E_SandwichDecoratorUserRecipe.Pepper THEN 
      CASE arrnStepOrder[nCurUserRecipeIndex] OF 
       E_SandwichDecoratorUserRecipe.Pepperoni: 
        nCurUserRecipeIndex := nCurUserRecipeIndex + 1; 

       E_SandwichDecoratorUserRecipe.Ham: 
        nCurUserRecipeIndex := nCurUserRecipeIndex + 1; 

       E_SandwichDecoratorUserRecipe.Cheese: 
        nCurUserRecipeIndex := nCurUserRecipeIndex + 1; 

       E_SandwichDecoratorUserRecipe.Tomato: 
        nCurUserRecipeIndex := nCurUserRecipeIndex + 1; 

       E_SandwichDecoratorUserRecipe.Salad: 
        nCurUserRecipeIndex := nCurUserRecipeIndex + 1; 

       E_SandwichDecoratorUserRecipe.Sauce: 
        nCurUserRecipeIndex := nCurUserRecipeIndex + 1; 

       E_SandwichDecoratorUserRecipe.Salt: 
        nCurUserRecipeIndex := nCurUserRecipeIndex + 1; 

       E_SandwichDecoratorUserRecipe.Pepper: 
        nCurUserRecipeIndex := nCurUserRecipeIndex + 1; 
      END_CASE 
     ELSE 
      nCurUserRecipeIndex := 1; 
      eCurStep := E_SandwichDecoratorStep.Finished; 
     END_IF 

    E_SandwichDecoratorStep.Finished: 
     IF bRestart THEN 
      bRestart := FALSE; 
      eCurStep := E_SandwichDecoratorStep.UserSelecting; 
     END_IF 

END_CASE