VEGA VEGAPULS 66 (≥ 2.0.0 - ≤ 3.8) Profibus PA - Manual (Page 59)

Byte-No. 1 2 3 4 5
Status
Status
(FB1)
IEEE-754-
Floating point value
PA-OUT
(FB1)
Format
Value
Note:
Bytes 6-10 are not used in this example.
Data format of the output signal
Byte4 Byte3 Byte2 Byte1 Byte0
Status Value (IEEE-754)
Fig. 37: 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. 38: Data format of the measured value
Coding of the status byte associated with the PA output value
Status
code Description according to Pro-
fibus standard Possible cause
0 x 00 bad - non-specific Flash-Update active
0 x 04 bad - configuration error l Adjustment error
l Configuration error with PV-Scale (PV-Span too small)
l Unit irregularity
l Error in the linearization table
VEGAPULS 66 • Profibus PA 59
10 Supplement
28448
-EN
-090305