VEGA WEIGHTRAC 31 Profibus PA - Manual (Page 72)

72
10 Supplement
WEIGHTRAC 31 • Profibus PA
43837-EN-131119
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
For-
mat
IEEE-754-Floating point
value
Sta-
tus
IEEE-754-Floating point
value
Sta-
tus
IEEE-754-Floating point
value
Sta-
tus
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. 38: 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.