IEC operator⮫ “Overview”: Binary selection.
OUT := SEL(G, IN0, IN1) means:
OUT := IN0 if G=FALSE;
OUT := IN1 if G=TRUE
IN0, IN1 and OUT can be any type of variable, G must be BOOL. The result of the selection is IN0 if G is FALSE, IN1 if G is TRUE.
Example in ST:
Var1:=SEL(TRUE,3,4); (* Result is 4 *)
Example in FBD:
An expression occurring ahead of IN1 or IN2 will not be processed if IN0 is TRUE.