VEGA VEGABAR 54 Profibus PA - Manual (Page 54)

54
10 Supplement
VEGABAR 54 • Profibus PA
36729-EN-130321
Data format of the output signal
Byte4 Byte3 Byte2 Byte1 Byte0
Status Value (IEEE-754)
Fig. 28: 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. 29: Data format of the measured value
Coding of the status byte associated with the PA output value
Status
code
Description according to
Profibus standard
Possible cause
0 x 00 bad - non-specific Flash-Update active
0 x 04 bad - configuration error – Adjustment error
– Configuration error with PV-Scale (PV-Span too small)
– Unit irregularity
– Error in the linearization table
0 x 0C bad - sensor failure – Hardware error
– Converter error
– Leakage pulse error
– Trigger error
0 x 10 bad - sensor failure – Measured value generation error
– 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 al-
ready valid measured value since switching on)
0 x 48 uncertain substitute set – Switch on simulation
– 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)
0 x 51 uncertain - sensor; conversion
not accurate - low limited
Sensor value < lower limit
0 x 52 uncertain - sensor; conversion
not accurate - high limited
Sensor value > upper limit
0 x 80 good (non-cascade) - OK OK
0 x 84 good (non-cascade) - active
block alarm
Static revision (FB, TB) changed (10 sec. active, after the parame-
ter of the static category has been written)