Data Structure Data Type - Siemens SIMATIC S7 System Manual

97BPLC concepts
4.4 Data types
To create an array from the block interface editor, name the array and choose data type
"Array [lo .. hi] of type", then edit "lo", "hi", and "type" as follows:
● lo - the starting (lowest) index for your array
● hi - the ending (highest) index for your array
● type - one of the data types, such as BOOL, SINT, UDINT
Table 4- 25 ARRAY data type rules
Data Type Array syntax
ARRAY Name [index1_min..index1_max, index2_min..index2_max] of <data type>
All array elements must be the same data type.

The index can be negative, but the lower limit must be less than or equal to the upper limit.

Arrays can have one to six dimensions.

Multi-dimensional index min..max declarations are separated by comma characters.

Nested arrays, or arrays of arrays, are not allowed.

The memory size of an array = (size of one element * total number of elements in array)

Array index
Constant or
variable
Example: array
declarations
Example: array
addresses
4.4.5

Data structure data type

You can use the data type "Struct" to define a structure of data consisting of other data
types. The struct data type can be used to handle a group of related process data as a single
data unit. A Struct data type is named and the internal data structure declared in the data
block editor or a block interface editor.
Arrays and structures can also be assembled into a larger structure. A structure can be
nested up to eight levels deep. For example, you can create a structure of structures that
contain arrays.
92
Valid index data types
USInt, SInt, UInt, Int, UDInt,
DInt
ARRAY[1..20] of REAL
ARRAY[-5..5] of INT
ARRAY[1..2, 3..4] of CHAR
ARRAY1[0]
ARRAY2[1,2]
ARRAY3[i,j]
Array index rules
Value limits: -32768 to +32767

Valid: Mixed constants and variables

Valid: Constant expressions

Not valid: Variable expressions

One dimension, 20 elements
One dimension, 11 elements
Two dimensions, 4 elements
ARRAY1 element 0
ARRAY2 element [1,2]
If i =3 and j=4, then ARRAY3 element
[3, 4] is addressed
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05