Byte-No.
1 2 3 4 5 6 7 8 9 10
Format
Value
IEEE-754-
Flieskommazahl
PA-OUT
(FB1)
Status
Status
(FB1)
IEEE-754-
Flieskommazahl
Temperature
(FB2)
Status
Status
(FB2)
Fig. 32: Telegram configuration example 2
Exa
mple 3 with pressure value and additional cyclical value without temperature value:
l AI (PA-OUT)
l Free Place
l Additional Cyclic Value
Byte-No.
1 2 3 4 5 6 7 8 9 10
Status
Status
Status
Status
(FB1)
IEEE-754-
Floating point value
PA-OUT
(FB1)
IEEE-754-
Floating point value
Additional Cyclic
Value
Format
Value
Fig. 33: Telegram configuration example 3
Data
format of the output signal
Byte4
Byte3
Byte2
Byte1
Byte0
Status Value (IEEE-754)
Fig. 34: Data format of
the output signal
The status byte corresponds to profile 3.0 "Profibus PA Profile for Process Control Devices" coded.
The status "Measured value OK" is coded a s 80 (hex) (Bit7 = 1, Bit6 … 0 = 0).
The measured value is transferred as a 32 bit floating point number in the IEEE-754 format.
Byte n
Byte n+1
Bit
7
VZ
Exponent
Bit
6
2
Bit
5
2
Bit
4
2
Bit
3
2
Bit
2
2
Bit
1
2
Bit
0
2
Bit
7
2
Bit
6
2
Bit
5
2
Bit
4
2
Bit
3
2
Bit
2
2
Bit
1
2
Bit
0
2
Sign
Bit
Significant
7
6 5
4
3
2 1
0
-1
-2
-3
-4
-5
-6
-7
Byte n+2
Byte n+3
Bit
7
2
Significant
Bit
6
2
Bit
5
2
Bit
4
2
Bit
3
2
Bit
2
2
Bit
1
2
Bit
0
2
Bit
7
2
Bit
6
2
Bit
5
2
Bit
4
2
Bit
3
2
Bit
2
2
Bit
1
2
Bit
0
2
Significant
-9
-10 -11
-12
-13
-14 -15
-16
-17
-18
-19
-20
-21
-22
-23
-8
Value = (-1)
VZ
2
(Exponent - 127)
(1 + Significant)
Fig. 35: Data format of
the measured value
VEGABAR 64 • Profibus PA 65
10 Supplement
28252-EN-081209
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