3 data format of the output signal – VEGA VEGASON 51P…53P Profibus PA User Manual
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VEGASON 51P … 53P
Technical data
3.3 Data format of the output signal
Byte4
Byte3
Byte2
Byte1
Byte0
Status
Meas. value (IEEE-754 format, see below)
Status byte:
The status byte corresponds to the profile 3.0 "Profibus PA Profile for Process Control De-
vices“ coded. The status "Meas. value OK“ is coded as 80 (hex) (Bit7 = 1, Bit 6 … 0 = 0).
Meas. value:
The meas. value is transferred as a 32 Bit floating point number in IEEE-754 format.
Byte n
Byte n+1
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
VZ
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
2
-1
2
-2
2
-3
2
-4
2
-5
2
-6
2
-7
Sign
Exponent
Mantissa
Byte n+2
Byte n+3
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
2
-8
2
-9
2
-10
2
-11
2
-12
2
-13
2
-14
2
-15
2
-16
2
-17
2
-18
2
-19
2
-20
2
-21
2
-22
2
-23
Mantissa
Mantissa
Formula:
Meas. value = (-1)
VZ
• 2
(Exponent - 127)
• (1 + Mantissa)
Examples:
41 70 00 00 (hex) = 0100 0001 0111 0000 0000 0000 0000 0000 (bin)
Meas. value
= (-1)
0
• 2
(130 - 127)
• (1 + 2
-1
+ 2
-2
+ 2
-3
)
= 1 • 2
3
• (1 + 0.5 + 0.25 + 0.125)
= 1 • 8 • 1.875
= 15.0