VEGA VEGACAL 64 Profibus PA - Manual (Page 43)

43
10 Supplement
VEGACAL 64 • Profibus PA
30031-EN-130917
– This module must be used if a value should not be used in the data telegram of the cyclical
data traffic (e.g. replacement of the 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 (standard setting) with distance value and additional cyclical value:
•
AI (PA-OUT)
•
Additional Cyclic Value
Byte-No. 1 2 3 4 5 6 7 8 9 10
Status
Status
Status
Status
(FB1)
IEEE-754-
Floating point value
PA-OUT
(FB1)
IEEE-754-
Floating point value
Additional Cyclic
Value
Format
Value
Example 2 with distance value without additional cyclical value:
•
AI (PA-OUT)
•
Free Place
Byte-No. 1 2 3 4 5
Status
Status
(FB1)
IEEE-754-
Floating point value
PA-OUT
(FB1)
Format
Value
Data format of the output signal
Byte4 Byte3 Byte2 Byte1 Byte0
Status Value (IEEE-754)
Fig. 28: Data format of the output signal
The status byte corresponds to profile 3.0 "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.