Honeywell HC900 User Manual page 16

IEEE 32-bit Floating Point Register Information
IEEE Floating Point Data Format
Exponent
The exponent is defined by an unsigned 8-bit binary value (bits 23 through 30). The value of the exponent
is derived by performing a signed subtraction of 127 (decimal) from the 8-bit exponent value.
DECIMAL HEXADECIMAL
100 42C80000
Removing the sign and mantissa bits, the exponent becomes:
DECIMAL HEXADECIMAL
133 85
or:
7 6
1x2  0 2 x 
Subtract a bias of 127 (decimal) from the exponent to determine its value: 133 – 127 = 6.
Mantissa and Exponent Combination
Combining the mantissa and exponent from the two previous examples:
Below is a list of sample float values in IEEE format:
8
BINARY
01000010 11001000 00000000 00000000
BINARY
x1000010 1xxxxxxx xxxxxxxx xxxxxxxx
5 4 3
0 x2  0 x2  0 x2 
float number = mantissa x 2
float number = 1.5625 x 2
DECIMAL
100.0
-100.0
0.5
-1.75
0.0625
1
0
HC900 Process Controller Communications User Guide
2 1 0
1 x2  0 x2  1 x2
exponent
6  15625 . x 64 = 100.0
HEXADECIMAL
42C80000
C2C80000
3F000000
BFE00000
3D800000
3F800000
00000000
Revision 13
April 2017