Data Type Prefix

Standard Data Types

The data type prefix identifies the data type of variables and constants.

NOTE: The data type prefix can also be composite, for example, for pointers, references and arrays. The pointer or array is listed first, followed by the prefix of the pointer type or array type.

The IEC 61131-3 standard data type prefixes as well as the prefixes for the extensions to the standard are listed in the table.

Data type prefix	Type	Use (memory location)	Example
`x`	BOOL	boolean (8 bit)	`xName`
`by`	BYTE	bit sequence (8 bit)	`byName`
`w`	WORD	bit sequence (16 bit)	`wName`
`dw`	DWORD	bit sequence (32 bit)	`dwName`
`lw`	LWORD	bit sequence (64 bit)	`lwName`
`si`	SINT	short integer (8 bit)	`siName`
`i`	INT	integer (16 bit)	`iName`
`di`	DINT	doubled integer (32 bit)	`diName`
`li`	LINT	long integer (64 bit)	`liName`
`uli`	ULINT	long integer (64 bit)	`uliName`
`usi`	USINT	short integer (8 bit)	`usiName`
`ui`	UINT	integer (16 bit)	`uiName`
`udi`	UDINT	doubled integer (32 bit)	`udiName`
`r`	REAL	floating-point number (32 bit)	`rName`
`lr`	LREAL	doubled floating-point number (64 bit)	`lrName`
`dat`	DATE	date (32 bit)	`datName`
`t`	TOD	time (32 bit)	`tName`
`dt`	DT	date and time (32 bit)	`dtName`
`tim`	TIME	duration (32 bit)	`timName`
`ltim`	LTIME	duration (64 bit)	`ltimName`
`s`	STRING	character string ASCII	`sName`
`ws`	WSTRING	character string unicode	`wsName`
`p`	pointers	pointer	`pxName`
`r`	reference	reference	`rxName`
`a`	array	field	`axName`
`e`	enumeration	list type	`eName`
`st`	struct	structure	`stName`
`if`	interface	interface	`ifMotion`
`ut`	union	union	`uName`
`fb`	function block	function block	`fbName`

Examples

piCounter: POINTER TO INT;
aiCounters: ARRAY [1..22] OF INT;
paiRefCounter: POINTER TO ARRAY [1..22] OF INT;
apstTest   : ARRAY[1..2] OF POINTER TO ST_MotionStructure;
rdiCounter : REFERENCE TO DINT;
ifMotion   : IF_Motion;