VEGA VEGAPULS SR 68 Profibus PA - Manual (Page 76)

76
11 Supplement
VEGAPULS SR 68 • Profibus PA
38296-EN-130624
Data format of the output signal
Byte4 Byte3 Byte2 Byte1 Byte0
Status Value (IEEE-754)
Fig. 57: Data format of the output signal
The status byte corresponds to profile 3.02 "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. 58: Data format of the measured value
Coding of the status byte associated with the PA output value
You can find further information for the coding of the status byte in the Device Description 3.02 on
www.profibus.com.
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 con-
stant
"Out of Service" mode switched on
0 x 44 uncertain - last unstable
value
Failsafe replacement value (Failsafe-Mode = "Last val-
ue" and already 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)