COMMISSIONING / OPERATION
4
17
H250 M40 ESK4
www.krohne.com
03/2014 - 4002251801 - AD H250/M40 PROFIBUS R01 en
4.6 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.
4.6.1 Input data
Input data is transferred from the ESK4-PA transmitter to the master for the measuring value
and the totalizer values. The format is the same for both. 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 following example describes 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
AD_H250_M40_PB_PA_R01_en_4002251801_PRT.book Page 17 Friday, March 21, 2014 1:14 PM
