KROHNE FC 300 Converter PROFIBUS PA-DP - Manual (Page 25)

APPLICATION PROFILE
4
25
IFC 300
www.krohne.com 02/2011 - 4001086601 - AD IFC 300 PROFIBUS R01 en
4.1 Function blocks
The PROFIBUS MBP interface is based on the PROFIBUS PA Profile Version 3.0 and supports the
following blocks:
• 1 physical block.
This block contains the parameters defined in PA Profile 3.0.
• 1 transducer block for electromagnetic flow devices.
This block provides the parameters and functions defined in PA Profile 3.0.
• 5 Analog Input (AI) function blocks.
As default: Volume Flow / Mass Flow / Speed Flow / Coil Temperature / Conductivity.
• 3 totalizer (TOT) function blocks.
As default the first two totalizers will totalize volume and the third one will totalize mass.
4.2 Data structure of function block output values
The data structure of function block outputs consists of 5 bytes: a 4 byte float value (Float Format
according IEEE Standard 754 Short Real Number) followed by a 1 byte status value. If all 8
function block outputs have been configured (see above), 40 bytes will be transmitted.
4.2.1 Float value
Example of 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