R_TRIG

VAR_INPUT

VAR_INPUT
    CLK : BOOL; (* Signal to detect *)
END_VAR

VAR_OUTPUT

VAR_OUTPUT
    Q : BOOL; (* Edge detected *)
END_VAR

The output Q will remain FALSE as long as the input variable CLK is FALSE. As soon as CLK returns TRUE, Q will return TRUE. This means each time the function is called up, Q will return FALSE until CLK has falling edge followed by a rising edge.

Requirements