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System 182
Float 32
ba75504e07
04/2012
Note
The counting method of the Modbus registers and Modbus bits and the
allocation of MSB and LSB is different from the usual method of most
programming languages.
Counting start of the register
MSB* allocation of the register
LSB* allocation of the register
*MSB = Most significant bit, LSB = Least significant bit
7.4.4 Data formats
The sensor data in the sensor data block (see section 7.4.3) are
available in the Float 32, INT16 and INT8 data formats.
The data for the main and secondary measured values are transmitted
in the IEE-754 standard 32-bit floating point format.
Bit representation
MSB*
LSB*
S E E E E E E E
E M M M M M M M
M M M M M M M M
M M M M M M M M
MSB = Most significant bit, LSB = Least significant bit
If not all of the bits of the exponents are 0, the value is calculated
according to:
−
=
−
S
⋅
E
127
⋅
+
V
1
2
1 (
If all of the bits of the exponents are 0, the value is calculated according
to:
−
=
−
S
⋅
126
⋅
V
1
2
(
M
b
22
A value is 0 if all the bits of both the exponents as well as the mantissa
are 0.
Modbus
1
Bit 1
Bit 16
Byte
Bit
4
31 - 24
3
23 - 16
2
15 - 08
1
07 - 00
−
−
⋅
1
+
⋅
2
M
2
M
2
b
22
b
21
−
−
⋅
1
+
⋅
2
+
2
M
2
M
b
21
Modbus connection
Usually
0
Bit 15
Bit 0
S = sign (bit 31)
E = Exponent (Bit 30-23)
M = mantissa (bits 22-0)
−
+
⋅
3
+
+
M
2
...
M
b
20
b
−
−
⋅
3
+
+
⋅
2
...
M
2
b
20
b
0
−
⋅
23
2
)
0
23
)
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