VEGA VEGAFLEX 52P (Profibus PA) - Manual (Page 17)

VEGAFLEX 51P and 52P 17
Product description
1.8 Approvals
VEGAFLEX sensors are approved for StEx Zone 10.
Please note the attached approval documents if you want to use a sensor in Ex environment.
1.9 Data format of the output signal
Byte4 Byte3 Byte2 Byte1 Byte0
Status Meas. value (IEEE-754 format, see below)
Status byte:
The status byte corresponds to the profile 3.0 "Profibus PA Profile for Process Control De-
vices" coded. The status "Meas. value OK" is coded as 80 (hex) (Bit7 = 1, Bit 6 … 0 = 0).
Measured value:
The meas. value is transferred as 32 Bit floating point number in the IEEE-754 format.
Byte n Byte n+1
Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
VZ 2 7 2 6 2 5 2 4 2 3 2 2 2 1 2 0 2 -1 2 -2 2 -3 2 -4 2 -5 2 -6 2 -7
Sign
Exponent Mantissa
Byte n+2 Byte n+3
Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit Bit
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
2 -8 2 -9 2 -10 2 -11 2 -12 2 -13 2 -14 2 -15 2 -16 2 -17 2 -18 2 -19 2 -20 2 -21 2 -22 2 -23
Mantissa Mantissa
Formula: Meas. value = (-1) VZ • 2 (Exponent - 127) • (1 + Mantissa)
Examples: 41 70 00 00 (hex) = 0100 0001 0111 0000 0000 0000 0000 0000 (bin)
Meas. value
= (-1) 0 • 2 (130 - 127) • (1 + 2 -1 + 2 -2 + 2 -3 )
= 1 • 2 3 • (1 + 0.5 + 0.25 + 0.125)
= 1 • 8 • 1.875
= 15.0