Honeywell HC900 - Table 3-2 IEEE Floating Point Number Examples in FP B Format; Figure 3-1 IEEE Floating Point Formats

Modbus Double Register Format
IEEE Floating Point Formats
12 HC900 Process Controller Communications User Guide Revision 13
April 2017
REGISTER N
(High)
REGISTER N+1
(Low)
High Low High Low
FP L - Floating Point Little Endian Format:
S=Sign E=Exponent M=Mantissa
E0 M22 M21M20 M19 M18 M17 M16
Bit 23
Bit 16
S E7 E6 E5 E4 E3 E2 E1
Bit 31
Bit 24
M7 M6 M5 M4 M3 M2 M1 M0
Bit 7
Bit 0
M15 M14 M13 M12 M11 M10 M9 M8
Bit 8Bit 15
REGISTER N
(High)
REGISTER N+1
(Low)
High Low High Low
FP LB - Floating Point Little Endian with Byte Swapped Format:
S=Sign E=Exponent M=Mantissa
E0 M22 M21M20 M19 M18 M17 M16
Bit 23
Bit 16
S E7 E6 E5 E4 E3 E2 E1
Bit 31
Bit 24
M7 M6 M5 M4 M3 M2 M1 M0
Bit 7
Bit 0
M15 M14 M13 M12 M11 M10 M9 M8
Bit 8Bit 15
Figure 3-1 IEEE Floating Point Formats
Table 3-2 IEEE Floating Point Number Examples in FP B Format
Value
(decimal)
IEEE FP B
MSB LSB
Register N
Register N+1
high
low
high
low
100.0
42C80000h
42h
C8h
00h
00h
55.32
425D47AEh
42h
5Dh
47h
AEh
2.0
40000000h
40h
00h
00h
00h
1.0
3F800000h
3Fh
80h
00h
00h
-1.0
BF800000h
BFh
80h
00h
00h