Interfaces to automation systems
8.1 PROFIBUS DP interface
SITRANS SL
132
Operating Instructions, 12/2010, A5E01132948-04
8.1.4
Cyclic data transmission over PROFIBUS
8.1.4.1
Cyclic data structure
Specific parameters physical block for passive bus tap-off
The following user data can be exchanged cyclically using the PROFIBUS.
Parameter name
Meaning
Direction seen
from gas analyzer
Data type
Length in byte
Concentration
Measured value
and status.
Output
DS-33
5
Transmission
Measured value
and status.
Output
DS-33
5
Pressure
Process pressure
in mbar.
Input
DS-33
5
Temperature
Process
temperature in
Celsius Degree.
Input
DS-33
5
DS 33 data type
Each value is represented as a 5 bytes value. The first four bytes build the measurement
value, transmitted according to IEEE-754. The fifth byte is used for status.
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Value in IEEE-754 floating point
Status
Exponent
Fraction
-
MSB
-
-