CODEWITHSUNDEEP
plctwincat
Snake56Snake
Snake56Snake

Reputation: 65

How to call the code from the basis FB when using extending at a Twincat

I would like to extend a FB but i need to call the code of the basis FB.

example Code

FB_Basis

FUNCTION_BLOCK FB_Basis
VAR_INPUT
    bInTest : BOOL;
END_VAR
VAR_OUTPUT
    nOutTest    : INT;
END_VAR

IF bInTest THEN
    nOutTest    := nOutTest + 1;
END_IF

FB_Test

FUNCTION_BLOCK FB_Test EXTENDS FB_Basis
VAR_INPUT
    bInTest2    : BOOL;
END_VAR
VAR_OUTPUT
    nOutTest2   : INT;
END_VAR

IF bInTest2 THEN
    nOutTest2   := nOutTest2 + 1;
END_IF

The Call:

FB_Test(  bInTest:= 
        , nOutTest=> 
        , bInTest2:= 
        , nOutTest2=> 
        );

If I set bInTest at TRUE I want the Output nOutTest count up but it doesn't.

I can't find information how to handle code from the FB_basis in the InfoSys from Beckhoff the just explain the behavior of methods.

I don't know how to call the code, would be thankful for answers.

Upvotes: 2

Views: 594

Answers (1)

Roald
Roald

Reputation: 2979

You can use SUPER^() to call the body of the parent function block. You need to add this to the body of FB_Test:

FUNCTION_BLOCK FB_Test EXTENDS FB_Basis
VAR_INPUT
    bInTest2    : BOOL;
END_VAR
VAR_OUTPUT
    nOutTest2   : INT;
END_VAR

SUPER^(); // Call the body of FB_Basis
IF bInTest2 THEN
    nOutTest2   := nOutTest2 + 1;
END_IF

Upvotes: 3

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