Omron SYSMAC CJ - REFERENCE MANUAL 08-2008 Reference Manual page 692

Double-precision Floating-point Instructions (CS1-H, CJ1-H, CJ1M, or CS1D Only)
Number of Digits
Floating-point Data
Special Numbers
Writing Floating-point
Data
652
Data No. of bits
s: sign 1
e: exponent 11
f: mantissa 52
Fifteen digits are effective for double-precision floating-point data.
The following data can be expressed by floating-point data:
• –
• –1.79769313486232 x 10
• 0
• 2.22507385850720 x 10
• +
• Not a number (NaN)
2.22507385850720 10 -
1.79769313486232 10
The formats for NaN,
NaN*: e = 2,047 and f
+ : e = 2,047, f = 0, and s= 0
– : e = 2,047, f = 0, and s= 1
0: e = 0 and f = 0
*NaN (not a number) is not a valid floating-point number. Executing Double-
precision Floating-point instructions will not result in NaN.
When double-precision floating-point is specified for the data format in the I/O
memory edit display in the CX-Programmer, standard decimal numbers input
in the display are automatically converted to the double-precision floating-
point format shown above (IEEE754-format) and written to I/O Memory. Data
written in the IEEE754-format is automatically converted to standard decimal
format when monitored on the display.
s e
6362
n+3
It is not necessary for the user to be aware of the IEEE754 data format when
reading and writing double-precision floating-point data. It is only necessary to
remember that double-precision floating point values occupy four words each.
0: positive; 1: negative
The exponent (e) value ranges from 0 to 2,047.
The actual exponent is the value remaining after
1,023 is subtracted from e, resulting in a range
of –1,023 to 1,024. "e=0" and "e=2,047" express
special numbers.
The mantissa portion of binary floating-point
data fits the format 2.0 > 1.f 1.0.
308
value –2.22507385850720 x 10
–308
value 1.79769313486232 x 10
2.22507385850720 10 -
308
1 1
0
308
1.79769313486232 10
, and 0 are as follows:
0
f
5251 4847 3231 1615
n+2 n+1
Section 3-16
Contents
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30
308
+
308
0
n