Siemens SIMATIC S7-1200

PLC concepts
5.4 Data types
S7-1200 Programmable controller
132 System Manual, V4.2, 09/2016, A5E02486680-AK
5.4.6
Array data type
Arrays
You can create an array that contains multiple elements of the same data type. Arrays can
be created in the block interface editors for OB, FC, FB, and DB. You cannot create an array
in the PLC tags editor.
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 5- 39 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
Valid index data types
Array index rules
Constant or varia-
ble
USInt, SInt, UInt, Int, UDInt,
DInt
• Value limits: -32768 to +32767
• Valid: Mixed constants and variables
• Valid: Constant expressions
• Not valid: Variable expressions
Example: array
declarations
ARRAY[1..20] of REAL
One dimension, 20 elements
ARRAY[-5..5] of INT
One dimension, 11 elements
ARRAY[1..2, 3..4] of CHAR
Two dimensions, 4 elements
Example: array
addresses
ARRAY1[0]
ARRAY1 element 0
ARRAY2[1,2]
ARRAY2 element [1,2]
ARRAY3[i,j]
If i =3 and j=4, then ARRAY3 element
[3, 4] is addressed