Siemens DS Betriebsanleitung Seite 28

Operating Instructions
Master
(Class 1)
(field devices, distributed I/Os, subordinate
controllers, network transition to
PROFIBUS-PA)
Figure 1 Typical PROFIBUS automation system
Figure 1 shows a section of a typical PROFIBUS automation system. The
control system comprises two masters with distributed tasks. The master
class 1 is the automation system and handles the control tasks. The master
class 2 permits parameterization, diagnosis and visualization of further field
device data. The measuring and control data are exchanged cyclically be-
tween master 1 and the field devices. The status information of the field de-
vices is transmitted parallel to this. In addition to cyclic mode, one or more
masters of class 2 can acyclically access the field devices, thus fetching fur-
ther information or changing settings. The control system receives the in-
formation required for establishment of the connection via the device-spe-
cific basic file GSD (see Chapter 4.2 and Appendix).
24
PROFIBUS-DP
Slaves
Master
(Class 2)
PROFIBUS-PA
I
C79000-B5674-C207-1
8
x
SITRANS P