Rockwell Automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command - Manual (Page 201)

11–5 Data Encoding
Publication 1770Ć6.5.16 - October 1996
Octal
The octal number system is another easy way to represent binary
data. This system uses the eight digits, 0 through 7. Each group of
three data bits represents one octal digit between 0 and 7. This factor
presents a slight conversion problem because bytes and words
usually contain an even number of bits. Thus, an 8-bit byte can have
an octal value between 0 and 377, while a 16-bit word can have an
octal value between 0 and 177777.
Each digit of an octal number has a place value that is a multiple
of 8. To convert from octal to decimal, multiply each octal digit
by its corresponding place value and add the results of the
multiplications.
Octal Representation of Decimal 239
1 x 2 1 = 2
1 x 2 0 = 1
1 x 2 2 = 4
0 x 2 1 = 0
1 x 2 0 = 1
1 x 2 2 = 4
1 x 2 1 = 2
1 x 2 0 = 1
1 1 1 0 1 1 1 1
3 x 8 2 = 192
5 x 8 1 = 40
7 x 8 0 = 7
= 357
8
239
10
Binary FloatingĆpoint
Use the binary floating-point numbering system when you want to
manipulate numbers outside of the range –32768 to +32768 or for a
resolution finer than one unit, for example 2.075.
SLC 5/03 OS300, SLC 5/04 OS400, and PLC-5 classic processors do
not support unnormalized, Not a Number (NaN), and infinity; PLC-5
enhanced processors support both NaN and infinity.
The valid range for a binary floating-point number is
$3.402824 x
10 38 to
$1.1754944 x 10 –38
.