Response For Class (RFC)

Title short form	RFC
Categories	Maintainability, reusability
Definition	Number of different POUs, methods or actions that can be called by a POU
Further information	RFC = Response For Class The value is used for measuring the complexity (in terms of testability and maintainability). All possible direct and indirect method calls can be reached via associations are taken into account. These can be used to respond to an incoming message or to respond to an event that has occurred.

Sample:

Function block FB1:

FUNCTION_BLOCK FB1
VAR
    d,x,y : INT;
END_VAR

x := METH(d+10);
y := FUN(42, 0.815);

Method FB1.METH:

METHOD METH : INT
VAR_INPUT
    i     : INT;
END_VAR

METH := FUN(CUBE(i), 3.1415);

Function Cube:

FUNCTION CUBE : INT
VAR_INPUT
    i     : INT;
END_VAR

CUBE := i*i*i;

Function FUN:

FUNCTION FUN : INT
VAR_INPUT
    a     : INT;
    f     : LREAL;
END_VAR

FUN := LREAL_TO_INT(f*10)*a;

FUN, CUBE: These functions have an RFC of 0, as neither function calls other functions, function blocks or methods for their calculations.
FB1.METH: The method uses FUN and CUBE, which results in an RFC of 2.
FB1:

The function block FB1 calls METH and FUN, which increases its RFC by 2.
For FB1, its method METH must also be taken into account. METH uses FUN and CUBE. FUN has already been added to the RFC of FB1 (see previous point). Thus, only the use of CUBE in METH increases the RFC for FB1 to 3.