to pop up its description (if any).
ALGORITHM REQ IN ST :
OUT := (X-Y)*(X+Y);
END_ALGORITHM
Upon the occurrence of an event at its
REQ
input, an instance of this Simple Function
Block type computes the value of its
OUT
variable, followed by an event at its
CNF
output. The
OUT
value is computed via the
REQ
algorithm shown above, which uses the IEC 61131-3 FBD (Function Block Diagram) graphical language to
implement the formula
The external interface and functionality of this FB type are the same as for the X2Y2 and X2Y2_FBD
types, and its execution control is the same as for the
X2Y2_FBD
type. The only difference is that in this FB type, the
REQ
algorithm is written in the IEC 61131-3 ST (Structured Text) language, as shown above.