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

Requirements