S7 SCL - Compare string from Block_DB

SeH · Jun 27, 2011

Hi

I'm having some problems comparing a string to an element from a Block_DB. My code look like this right now (I've removed some parts).

Code:

FUNCTION_BLOCK  Recipe_handling

    VAR
        area_start : INT;
        active_start : INT := 0;
    END_VAR
    
    VAR_INPUT
        recipe : BLOCK_DB;
    END_VAR
    
    VAR_IN_OUT
        article_nr : STRING[50];
    END_VAR
    
    BEGIN    
    WHILE EQ_STRNG(S1:=article_nr, S2:=REAL_TO_STRING(DWORD_TO_REAL(recipe.DD[area_start]))) DO
            ;
     END_WHILE;
    ;
END_FUNCTION_BLOCK

When I try to compile i get an error saying "Illegal parameter transfer". Does anyone know how to solve this?

Thanks

L D[AR2P#0.0] · Jun 27, 2011

You cannot pass a string IN_OUT parameter on to another block. You will have to copy the in_out string to another variable before performing the string compare. e.g.

Code:

FUNCTION_BLOCK  FB888
    VAR
        area_start : INT;
        active_start : INT := 0;
        sComp:STRING[50];
    END_VAR
 
    VAR_INPUT
        recipe : BLOCK_DB;
    END_VAR
 
    VAR_IN_OUT
        article_nr : STRING[50];
    END_VAR
 
    BEGIN
    sComp:=article_nr;    
    WHILE EQ_STRNG(S1:=sComp, S2:=REAL_TO_STRING(DWORD_TO_REAL(recipe.DD[area_start]))) DO
            ;
     END_WHILE;
    ;
END_FUNCTION_BLOCK

SeH · Jun 27, 2011

Thank you L D[AR2,P#0.0] it work now

S7 SCL - Compare string from Block_DB

SeH

Member

L D[AR2P#0.0]

Lifetime Supporting Member

SeH

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