KROHNE OPTIWAVE 5200 PROFIBUS - Manual (Page 12)

4
COMMISSIONING / OPERATION
12
OPTIWAVE 5200 C
www.krohne.com 10/2013 - 4003066901 - MA OPTIWAVE5200C-PA-R01-en-
4.5 Cyclic data
In a PROFIBUS network cyclic data is described from the point of view of the master. Therefore
input data is transferred from the slave to the master while output data is transferred from the
master to the slave.
4.5.1 Input data
Input data is transferred from the level transmitter to the master for the measuring value. If
input data transfer is configured, 5 bytes are transferred for the corresponding slot:
• 4 byte float value (Float Format according to IEEE Standard 754 Short Real Number)
• 1 byte status value
Float value Float value Float value Float value
The example that follows shows the format of the float value according to IEEE Standard 754
Short Real Number:
Float format
Example (binary): 40 F0 00 00 (hex) = 0100 0000 1111 0000 0000 0000 0000 0000
Formula: Formula: Formula: Formula:
value = (-1)
VZ
* 2
(Exponent – 127)
* (1 + Mantissa)
value = (-1) 0 * 2 (129 – 127) * (1 + 2 -1 + 2 -2 + 2 -3 )
value = 1 * 4 * (1 + 0.5 + 0.25 + 0.125)
value = 7.5
Byte n Byte n+1
Bit7 Bit6 Bit7 Bit6
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
Exponent Mantissa
Byte n+2 Byte n+3
Bit7 Bit7
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