7. How to implement the PROFIBUS Master Class 1
7.1 Device Database Files (GSD)
The device database files are provided as a text file SAMS3785.GSD. They are available at
SAMSON AG under
Product no. 1400-7417
on a 1.44 MB disk 3 1/2". Or you can down-
load the files via Internet from the following sites:
http://www.samson.de
or
http: //www.profibus.com
.
The device database files enable the standardized implementation of the SAMSON Type
3785 PROFIBUS Positioner as a PROFIBUS slave unit in the programming and configuration
environment of a Master Class 1 (example: SIEMENS Simatic Step 7, HWConfig). Via the
GSD, the Master Class 1 is informed about the basic possibilities of cyclic data exchange
with the slave unit – in this case, the Type 3785 Positioner.
7.2 DATA EXCHANGE
According to the PROFIBUS PA device profile for electropneumatic actuators, a total of 7
different cyclic parameter combinations is available for the exchange of data. Via the pro-
gramming and configuration environment of the Master Class 1, you must select one of the
above mentioned seven combinations.
The terms output and input are based on the control system /Master Class 1.
Variant 1:
Module = "SP" 0xA4
Output value (Output)
Byte 0
1
2
3
4
Octet 1
Sign,
Exponent
Octet 2
Exponent,
Fraction
Octet 3
Fraction
Octet 4
Fraction
Octet 5
SP, Value
(Floating Point, IEEE)
Status
Variant 2:
Module = "RCAS_OUT, RCAS_IN " 0xB4
Input value (Input)
Byte 0
1
2
3
4
Octet 1
Sign,
Exponent
Octet 2
Exponent,
Fraction
Octet 3
Fraction
Octet 4
Fraction
Octet 5
RCAS_OUT, Value
(Floating Point, IEEE)
Status
36
EB 8382-1 EN
How to implement the PROFIBUS Master Class 1
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