VEGA VEGABAR 65 Profibus PA - Manual (Page 64)

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
Coding of the status byte associated with the PA output value
Status
code Description according to Pro-
fibus standard Possible cause
0x00 bad - non-specific Flash-Update active
0x04 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
0x0C bad - sensor failure l Hardware error
l Converter error
l Leakage pulse error
l Trigger error
0x10 bad - sensor failure l Measured value generation error
l Temperature measurement error
0 x 1f bad - out of service constant "Out of Service" mode switched on
0 x 44 uncertain - last unstable value Failsafe replacement value (Failsafe-Mode = "Last value" and
already valid measured value since switching on)
0 x 48 uncertain substitute set l Switch on simulation
l Failsafe replacement value (Failsafe-Mode = "Fsafe value")
0 x 4c uncertain - initial value Failsafe replacement value (Failsafe-Mode = "Last valid value" and
no valid measured value since switching on)
64 VEGABAR 65 • Profibus PA
10 Supplement
28253
-EN
-090522