Data Type ‘ARRAY’

CODESYS supports one, two, and three-dimensional arrays of elementary data types. You can define arrays in the declaration part of a block and in the global variable list.

Arrays of variable length can be used only VAR_IN_OUT variables of function blocks, methods, and functions can be declared with the data type of an array of variable length.

For arrays of variable length, the LOWER_BOUND(<array name>,<dim>) and UPPER_BOUND(array name,<dim>) operators yield the lower and upper limits.

Syntax for the declaration of an array with a defined length:

<array name> : ARRAY [<ll1>..<ul1>,<ll2>..<ul2>] OF <elem. type>

ll1, ll2, ll3 define the lower limit of a field dimension, and ul1, ul2 and ul3 define the upper limit. These limiting values must be integer values.

Example

Card_game: ARRAY [1..13, 1..4] OF INT;

Syntax for the declaration of an array with a variable length:

<array name> : ARRAY [\*|, \*|, \*] OF <data type>;

Example

FUNCTION SUM: INT;  // One-dimensional arrays of variable lengths can be passed to this addition function.
VAR_IN_OUT
 A: ARRAY [*] OF INT;
END_VAR
VAR
 i, sum2 : DINT;
END_VAR

sum2:= 0;
FOR i:= LOWER_BOUND(A,1) TO UPPER_BOUND(A,1)   // The length of the respective array is determined.
 sum2:= sum2 + A[i];
END_FOR;
SUM:= sum2;

Initializing arrays

Example of the full initialization of an array:

arr1 : ARRAY [1..5] OF INT := [1,2,3,4,5];
arr2 : ARRAY [1..2,3..4] OF INT := [1,3(7)]; (* short for 1,7,7,7 *)
arr3 : ARRAY [1..2,2..3,3..4] OF INT := [2(0),4(4),2,3];
\    (* short for 0,0,4,4,4,4,2,3 *)

Example of the initialization of an array of a structure:

Structure definition:

TYPE STRUCT1
STRUCT
 p1:int;
 p2:int;
 p3:dword;
END_STRUCT
END_TYPE

Array initialization:

ARRAY[1..3] OF STRUCT1:= [(p1:=1,p2:=10,p3:=4723),(p1:=2,p2:=0,p3:=299),(p1:=14,p2:=5,p3:=112)];

Example of the partial initialization of an array:

arr1 : ARRAY [1..10] OF INT := [1,2];

Elements that you explicitly did not assign initialization values are initialized with the default value of the basic data type. In the example above, CODESYS initializes the elements arr1[3] to arr1[10] with 0.

Example of the initialization of an array of function blocks with additional parameters in FB_init:

Function block FB and method FB_Init with two parameters:

FUNCTION_BLOCK FB
VAR
\ _nId : INT;
\ _lrIn : LREAL;
END_VAR

METHOD FB_Init : BOOL
VAR_INPUT
\ bInitRetains : BOOL;
\ bInCopyCode : BOOL;
\ nId : INT;
\ lrIn : LREAL;
END_VAR

_nId := nId;
_lrIn := lrIN;

Array declaration with initialization:

PROGRAM PLC_PRG
VAR
  inst : POU(nId := 11, lrIn := 33.44);
\  ainst : ARRAY [0..1, 0..1] OF POU[(nId := 12, lrIn := 11.22), (nId := 13, lrIn := 22.33), (nId := 14, lrIn := 33.55),(nId := 15, lrIn := 11.22)];
END_VAR

Access to array elements

In a two-dimensional array, you access the elements as follows:

<array name>[Index1,Index2]

Example

Card_game [9,2]

Note

Please note the capability of using the implicit monitoring function CheckBounds to monitor the violation of field limits in runtime mode.

See also

• POU ‘CheckBounds’