VEGA VEGABAR 64 Profibus PA User Manual
Page 65
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
Example 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 as 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