8
Installation and Operation Manual
X-DPT-Profibus-DP-Interface-eng
PN 541-C-068-AAG
November, 2008
1.3.2 Number representations and formats
Bit Smallest binary information representation: 0 or 1
Nibble Binary number representation, consists of 4 bits. Repre
sents 1 value or 4 situations (‘bitmapped’). Usually
nibbles appear grouped together in one or more bytes
(i.e. two per byte).
Examples:
Value: binary 0011 = 3 decimal
Bitmapped: binary 0111 = bits 0,1, and 2 are true, 3 is
false
Byte or Octet Binary number representation, consists of 8 bits. Repre
sents 1 value or 8 situations (‘bitmapped’). Bits in a byte
are numbered from right to left, i.e. least significant bit is
bit 0, most significant bit is bit 7.
Examples:
Value: binary 00110011 = 51 decimal
Bitmapped: binary 00010111 = bits 0,1,2 and 4 are true,
others are false
Word Combination of 2 bytes or 16 bits. Represents 1 value or
16 situations (‘bitmapped’).
Examples:
Value: binary 00010001 00110011 = 4404 decimal
Bitmapped: binary 00010001 00010111 = bits 0,1,2,4,8
and 12 are true, others are false.
Integer An integer is a whole number (not a fractional number) that
can be positive, negative, or zero.
Examples:
-5, 1, 5, 8, 97, and 3,043.
Decimal Common numbers in the decimal number system. Range
depends on size of the binary representation:
Examples:
1 binary byte: range 0..255 decimal
2 binary bytes = 1 binary word: range 0..65535
Hexadecimal Representation of numbers in the hexadecimal number
system. Any written hexadecimal number in this manual is
preceded by “0x”
Examples:
0x25 = hexadecimal 25 = decimal 37 (1 byte)
0xB4 = hexadecimal B4 = decimal 180 (1 byte)
Real Representation of fractional numbers according to IEEE-
754 single precision floating point format definition.
See also Appendix B
Size: 4 bytes
Range: ±3.4*10
-38
to ±3.4*10
+38
Examples:
0x41 0x45 0x70 0xA4 = decimal 12.34
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