B.4: Floating Point Values - Electro Industries Shark 100 Installation & Operation Manual

Low cost, high performance multifunction electricity meter
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B.4: Floating Point Values

Floating Point Values are represented in the following format:
Register
Byte
0
Bit
7
6
5
4
3
Meaning
s
e
e
e
e
sign
exponent
The formula to interpret a Floating Point Value is: -1
i
sign
137 127
1
x
2
x
1 11000010001110110111001
10
1 2
x
x
1.75871956
1800.929
Register
Byte
0x0C4
Bit
7
6
5
4
1
1
0
0
Meaning
s
e
e
e
sign
exponent
1
0x089 = 137
Formula Explanation
C4E11DB9 (hex)
The sign of the mantissa (and therefore the number) is 1, which represents a negative value.
The Exponent is 10001001 (binary) or 137 decimal.
The Exponent is a value in excess 127. So, the Exponent value is 10.
The Mantissa is 11000010001110110111001 binary.
With the implied leading 1, the Mantissa is (1).C23B72 (hex).
The Floating Point Representation is therefore -1.75871956 times 2 to the 10.
Decimal equivalent: -1800.929
NOTE:
Exponent = the whole number before the decimal point.
Mantissa = the positive fraction after the decimal point.
B.5: Modbus Register Map (MM-1 1 to MM-8 8 )
The Shark 100 Modbus Register Map begins on the following page.
e
Electro Industries/GaugeTech
0
1
2
1
0
7
6
5
4
e
e
e
e
m
m m
m
0x0C4E1
0x0E1
3
2
1
0
7
6
5
4
0
1
0
0
1
1
1
0
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
11000100 11100001 00011101 10111001 (binary)
3
2
1
0
7
6
5
4
m m m
m
m
m
m
mantissa
x 2
sign
exponent-127
3
2
1
0
7
6
5
0
0
0
1
0
0
0
0b011000010001110110111001
Doc # E145701
1
0
3
2
1
0
7
6
5
m m
m
m
m m m m m m m m
x1.mantissa = 0x0C4E11DB9
0x01DB9
0x01D
4
3
2
1
0
7
6
5
1
1
1
0
1
1
0
1
mantissa
1
4
3
2
1
0
0x0B9
4
3
2
1
0
1
1
0
0
1
B-2

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