‘<operator>’ needs at least ‘<number of operands>’ operands
Too few operands are assigned to an operator.
Assign the required number of operands to the operator.
PROGRAM PLC_PRG
VAR
i : INT;
END_VAR
i := MUX(30,40);
--> C0023: 'MUX' needs at least '3' operands
i := MUX(30,40,50);