VEGA VEGAFLEX 82 Profibus PA - Manual (Page 88)

88
11 Supplement
VEGAFLEX 82 • Profibus PA
44220-EN-130910
– This module must be used if a value in the data telegram of the cyclical data traffic should not
be used (e.g. replacement of temperature and Additional Cyclic Value)
A maximum of three modules can be active. By means of the configuration software of the Profibus
master you can determine the configuration of the cyclical data telegram with these modules. The
procedure depends on the respective configuration software.
Note:
The modules are available in two versions:
•
Short for Profibus master supporting only one "Identifier Format" byte, e.g. Allen
Bradley
•
Long for Profibus master only supporting the "Identifier Format" byte, e.g. Siemens
S7-300/400
Examples of telegram configuration
In the following you will see how the modules can be combined and how the appendant data tel-
egram is structured.
Example 1
•
AI FB1 (OUT)
•
AI FB2 (OUT)
•
AI FB3 (OUT)
Byte-
No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Format IEEE-754-Floating point
value
Status IEEE-754-Floating point
value
Status IEEE-754-Floating point
value
Status
Value AI FB1 (OUT) AI FB1 AI FB2 (OUT) AI FB2 AI FB3 (OUT) AI FB3
Example 2
•
AI FB1 (OUT)
•
Free Place
•
Free Place
Byte-No. 1 2 3 4 5
Format IEEE-754-Floating point value Status
Value AI FB1 (OUT) AI FB1
Note:
Bytes 6-15 are not used in this example.
Data format of the output signal
Byte4 Byte3 Byte2 Byte1 Byte0
Status Value (IEEE-754)
Fig. 65: Data format of the output signal
The status byte corresponds to profile 3.02 "Profibus PA Profile for Process Control Devices" coded.
The status "Measured value OK" is coded as 80 (hex) (Bit7 = 1, Bit6 … 0 = 0).
The measured value is transferred as a 32 bit floating point number in the IEEE-754 format.