Rockwell-automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command Manuale Utente Pagina 199

  • Scaricare
  • Aggiungi ai miei manuali
  • Stampa
  • Pagina
    / 251
  • Indice
  • SEGNALIBRI
  • Valutato. / 5. Basato su recensioni clienti
Vedere la pagina 198
11–3Data Encoding
Publication
17706.5.16 - October 1996
Binary
The binary numbering system is a simple method for computer and
PLC applications because it is the most natural way to represent data
bits. However, since the binary system uses the digits 0 and 1, it is
cumbersome to show values in binary format.
Each digit in a binary number has a place value expressed as a power
of 2. You calculate the decimal equivalent of a binary number by
multiplying each binary digit by its corresponding place value and
then adding the results of the multiplications.
Binary Representation, Number 239
Bit:
1
2
11 01111
76543 10
1 x 2
7
= 128
1 x 2
6
=64
1 x 2
5
=32
1 x 2
4
=
0
1 x 2
3
=8
1 x 2
2
=4
1 x 2
1
2
1 x 2
0
1
239
10
Binary Coded Decimal
PLC data is often represented in binary coded decimal (BCD) form.
In this system, each group of four bits in a PLC word represents one
decimal number between 0 and 9. In this way, each 16-bit word can
represent a BCD value between 0 and 9,999. Many PLCs use only a
three-digit BCD (12 bits). The upper digit (3 bits) is used for
information such as timer or counter status.
BCD Representation of Decimal 239
0011
third digit
0110
second digit
0100
first digit
0 x 2
3
= 0
0 x 2
2
= 0
1 x 2
1
= 2
0 x 2
0
= 0
0 x 2
3
= 0
0 x 2
2
= 0
1 x 2
1
= 2
1 x 2
0
= 1
1 x 2
3
= 8
0 x 2
2
= 0
0 x 2
1
= 0
1 x 2
0
= 1
= 2
10
= 3
10
= 9
10
= 239
10
Vedere la pagina 198
1 2 ... 194 195 196 197 198 199 200 201 202 203 204 ... 250 251

Commenti su questo manuale

Nessun commento