N1

Data type. Possible values are 0: VW, 1: IW, or 2: QW

N2

Initial address

N3

Type of variable. Possible values are 0: WORD, 1: STRING, 2: DWORD, 3:  DWORD2, 4: REAL, 5: REAL2, 10: INT, 12: DINT, or 13: DINT2. Please check topic Types of Variables for more information

N4

Size of a String. The maximum value is 509 bytes, if the type of variable is STRING, that is, the N3 parameter equal to 1 (one)