Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 233)

Numbering Systems
Appendix A
AĆ3
Each place value in a binary number represents a power of two starting with
two raised to the zero power (2
0 =1) (Figure A.3). You can compute the decimal
value of a binary number by multiplying each binary digit by its corresponding
place value and adding these numbers together.
Figure A.3
Binary Numbering System
1 1 1 0 1 1 1 1
1
128
64
32
8
4
2
1
1 x 2 7 = 128
1 x 2 6 = 64
1 x 2 5 = 32
0 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
11101111
2
= 239
10
2
Binary Coded Decimal
Binary coded decimal (BCD) format expresses a decimal value as an
arrangement of binary digits. Each group of 4 binary digits is used to represent
a decimal number from 0 to 9. All BCD numbers are composed of these digits.
The value of BCD number depends on the digits used and the place value of
these digits.
Each place value in a BCD number represents a power of two starting with two
raised to the zero power (2
0 =1) (Figure A.4).