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GFK-0467K Chapter 2 System Operation 2-23
2
Data Types
Data types include the following:
Table 2-5. Data Types
Type Name Description Data Format
INT Signed
Integer
Signed integers use 16-bit memory
data locations, and are represented
in 2’s complement notation. The
valid range of an INT data type is –32,768
to +32,767.
Register 1
(16 bit positions)
16 1
S|
DINT Double
Precision
Signed
Integer
Double precision signed integers are
stored in 32-bit data memory
locations (actually two consecutive 16-bit
memory locations) and represented in 2’s
complement notation. (Bit 32 is the sign
bit.) The valid range of a DINT data type
is –2,147,483,648 to +2,147,483,867.
Register 2
32 17
S|
Register 1
16 1
(Two’s Complement Value)
BIT Bit A Bit data type is the smallest unit of
memory. It has two states, 1 or 0. A BIT
string may have length N.
BYTE Byte A Byte data type has an 8-bit value.
The valid range is 0 to 255 (0 to FF in
hexadecimal).
WORD A Word data type uses 16 consecutive
bits of data memory; but, instead of the
bits in the data location
representing a number, the bits are
independent of each other. Each bit
represents its own binary state (1 or
0), and the bits are not looked at
together to represent an integer
number. The valid range of word
values is 0 to FFFF.
Register 1
(16 bit positions)
16 1
BCD-4 Four-Digit
Binary
Coded
Decimal
Four-digit BCD numbers use 16-bit data
memory locations. Each BCD
digit uses four bits and can represent
numbers between 0 and 9. This BCD
coding of the 16 bits has a legal value
range of 0 to 9999.
Register 1
(4 BCD digits)
16 13 9 5 1
4 |3 | 2 | 1
REAL Floating
Point
Real numbers use 32 consecutive bits
(actually two consecutive 16-bit memory
locations). The range of numbers that can
be stored in this format is from
±
1.401298E-45 to ± 3.402823E+38.
Register 2
32 17
S|
Register 1
16 1
(Two’s Complement Value)
S = Sign bit (0 = positive, 1 = negative).