SA0081: Upper border is not a constant

Detects the FOR statements where the upper bound is not defined with a constant value

Justification: If the upper bound of a loop is a variable value, then it is no longer possible to see how often a loop is executed. This can result in serious problems at runtime. The worst case is an infinite loop.

Importance: High

Example

PROGRAM PLC_PRG
VAR
	i:INT;
	iBorder1: INT := 10;
	iBorder2: INT := 10;
	iCounter: INT;
END_VAR
VAR CONSTANT
	ciBorder:INT := 10;
END_VAR

FOR i:=0 TO 10 DO	//OK
	iCounter := i;
END_FOR

FOR i:=0 TO ciBorder DO // OK
	iCounter := i;
END_FOR

FOR i:=0 TO iBorder1 DO	// SA0081
	iCounter := i;
END_FOR

FOR i:=0 TO iBorder2 DO	// SA0081
	iCounter := i;
	IF iCounter = 10 THEN
		iBorder2 := 50;
	END_IF
END_FOR

--> SA0081: Upper border of a for loop must be a constant value