SHL

Bitwise left-shift of an operand : A:= SHL (IN, N)A, IN and N should be of the type BYTE, WORD, or DWORD. IN will be shifted to the left by N bits and filled with zeros on the right.

Please note, that the amount of bits, which is regarded for the arithmetic operation, is pretended by the data type of the input variable! If the input variable is a constant the smallest possible data type is regarded. The data type of the output variable has no effect at all on the arithmetic operation.

See in the following example in hexadecimal notation that you get different results for erg_byte and erg_word depending on the data type of the input variable (BYTE or WORD), although the values of the input variables in_byte and in_word are the same.
Example in ST:

Example in IL:

LD 1

SHL 1

ST Var1 (* Result is 2 *)