Operator: ROL

The IEC operator is used for bitwise rotation of an operand to the left.

Permitted data types: ‎BYTE‎, ‎WORD‎, ‎DWORD‎, ‎LWORD‎

‎erg := ROL (in, n)‎

CODESYS moves ‎in‎ n-times one bit to the left and adds the bit to the leftmost position from the right.

NOTICE

Note the number of bits which CODESYS uses for this operation as defined by the data type of the ‎in‎ input variable. If this is a constant, then CODESYS uses the smallest possible data type. The data type of the output variables still does not influence this operation.

Examples

The results for ‎erg_byte‎ and ‎erg_word‎ are different depending on the data type of the input variables, although the values of the ‎in_byte‎ and ‎in_word‎ input variables are the same.

PROGRAM rol_st

VAR
 in_byte : BYTE := 16#45;
 in_word : WORD := 6#45;
 erg_byte : BYTE;
 erg_word : WORD;
 n: BYTE := 2;
END_VAR

erg_byte := ROL(in_byte,n); (* Result: 16#15 *)

erg_word := ROL(in_word,n); (* Result: 16#0114 *)

FBD