2 profibus pa – data format and status byte, 2 profibus pa - data format and status byte – VEGA VEGAFLEX 62 Profibus PA User Manual
Page 56
10.2 Profibus PA - Data format and status byte
Data format of the output signal
Byte4
Byte3
Byte2
Byte1 Byte0
Status
Value (IEEE-754)
Fig. 33: Data format of the output signal
Status byte:
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).
Measured value (Value):
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. 34: 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
0x1f
bad - out of service constant
"O
ut of Service" mode switched on
0x44
uncertain - last unstable value
Failsafe replacement value (Failsafe-Mode = "Last value" and
already valid measured value since switching on)
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VEGAFLEX
62 • Profibus PA
10 Supplement
31839
-EN
-100426