wtw DIQ/S 182-PR, System Operating Manual

Page: 120 / 146

PROFIBUS connection System 182
7 - 10 ba75503e07 04/2012
7.5.5 Data formats
Measured values The data for the main and secondary measured values are transmitted
in the IEE-754 standard 32-bit floating point format.
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:
If all of the bits of the exponents are 0, the value is calculated according
to:
A value is 0 if all the bits of both the exponents as well as the mantissa
are 0.
Note
If the measured value is equal to 0, check the measured value status.
If the measured value status is not equal to 1, an error has occurred
and the measured value is invalid.
Sensor model
Status info
The data for the sensor model and status info is transmitted as INT16,
i.e. consists of 2 bytes. The assignment is carried out in Motorola
format (the higher value byte first).
Measured value status The data for the measured value status of the main and secondary
measured values are encoded jointly into a single byte. Bits 7-4 encode
Address Bit representation
Offset 0h bits 31-24 S = sign (bit 31)
E = exponent
(bits 30-23)
M = mantissa (bits 22-0)
Offset 1h bits 23-16
Offset 2h bits 15-8
Offset 3h bits 7-0
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
) 2 ... 2 2 2 1 ( 2 1
23
0
3
20
2
21
1
22
127
− − − − −
⋅ + + ⋅ + ⋅ + ⋅ + ⋅ ⋅ − =
b b b b
E S
M M M M V
) 2 ... 2 2 2 ( 2 1
23
0
3
20
2
21
1
22
126
− − − − −
⋅ + + ⋅ + ⋅ + ⋅ ⋅ ⋅ − =
b b b b
S
M M M M V
Address Bit representation Information
Offset 0h bits 15-8 High byte
Offset 1h bits 7-0 Low byte
MSB LSB