Integer Data Types; Floating-Point Real Data Types - Siemens SIMATIC S7 System Manual

97BPLC concepts
4.4 Data types
4.4.2

Integer data types

Table 4- 17 Integer data types (U = unsigned, S = short, D= double)
Data type Bit size
USInt 8
SInt 8
UInt 16
Int 16
UDInt 32
DInt 32
4.4.3

Floating-point real data types

Real (or floating-point) numbers are represented as 32-bit single-precision numbers (Real),
or 64-bit double-precision numbers (LReal) as described in the ANSI/IEEE 754-1985
standard. Single-precision floating-point numbers are accurate up to 6 significant digits and
double-precision floating point numbers are accurate up to 15 significant digits. You can
specify a maximum of 6 significant digits (Real) or 15 (LReal) when entering a floating-point
constant to maintain precision.
Table 4- 18 Floating-point real data types (L=Long)
Data type Bit size Number range
Real 32 -3.402823e+38 to -1.175 495e-38,
±0,
+1.175 495e-38 to +3.402823e+38
LReal 64 -1.7976931348623158e+308 to
-2.2250738585072014e-308,
±0,
+2.2250738585072014e-308 to
+1.7976931348623158e+308
Calculations that involve a long series of values including very large and very small numbers
can produce inaccurate results. This can occur if the numbers differ by 10 to the power of x,
where x > 6 (Real), or 15 (LReal). For example (Real): 100 000 000 + 1 = 100 000 000.
88
Number Range Constant examples
0 to 255 78, 2#01001110
-128 to 127 +50, 16#50
0 to 65,535 65295, 0
-32,768 to 32,767 30000, +30000
0 to 4,294,967,295 4042322160
-2,147,483,648 to -2131754992
2,147,483,647
Address
examples
MB0, DB1.DBB4,
Tag_name
MW2, DB1.DBW2,
Tag_name
MD6, DB1.DBD8,
Tag_name
Constant Examples
123.456, -3.4, 1.0e-5
12345.123456789e40,
1.2E+40
System Manual, 11/2011, A5E02486680-05
Address examples
MD100, DB1.DBD8,
Tag_name
DB_name.var_name
Rules:
No direct addressing

support
Can be assigned in an

OB, FB, or FC block
interface table
Can be assigned in a

global or instance data
block , only when the data
block is created as the
"optimized" type (symbolic
access only)
S7-1200 Programmable controller