Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 235)

Numbering Systems
Appendix A
AĆ5
Binary Coded Octal
Binary coded octal (BCO) format expresses an octal value as an arrangement of
binary digits (eight bits or one byte). The 8 bits are broken down into three
groups: 2 bits, 3 bits and 3 bits. Each group of binary digits is used to represent
a decimal number from 0 to 9. All BCO numbers are composed of these digits.
Each place value in a BCD number represents a power of two 1 starting with
two raised to the zero power (2
0 = 1) (Figure A.5).
Figure A.5
Binary Coded Octal
1 1 1 0 1 1 1 1
10242
2 1 2 0 2 2 2 1 2 0 2 2 2 1 2 0
3 5 7
8
You can compute the octal number for each group of bits by multiplying the
binary digit by its corresponding place value and adding these numbers together
(Table A.C).
Table A.C
Octal Representation
Place Value
Octal Equivalent
2 2
(4)
2 1
(2)
2 0
(1)
0 0 0 0
0 0 1 1
0 1 0 2
0 1 1 3
1 0 0 4
1 0 1 5
1 1 0 6
1 1 1 7