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1.2.4 Profile
Control room
PLS, PC
T
Terminating resistor
FD
Field device
PC
Personal computer
PLS
Process control system
Figure 6
PROFIBUS PA architecture
1.2.5 Interfacing
SIPART PS2 PA Manual
A5E00127926--05
Supplementary to the EN standard 50170, the PNO (PROFIBUS
Userorganisation) has defined the functionality of the individual field
device types in a so--called profile description. This profile defines
minimum functional requirements and optional extensions. The
device--internal Device Management supplies all the basic information
necessary for finding the profile parameters to the control system
configuration tool. With this, a parametering tool can operate all
profile--conforming devices regardless of type and manufacturer.
Depending on the size of the system and thus the number of field
devices and the required timing, the system must be implemented with
one or more PROFIBUS PA channels. A PROFIBUS PA channel
consists of the components shown in Figure 6.
PROFIBUS-DP
Coupler
T
Power
supply
The central process control system PLS or, in the case of low
requirements, a PC, is responsible for the control.
As a rule the signal conversion DP/PA, bus feeding and bus termination
functions are combined in a coupling module. Depending on the
number of PROFIBUS PA field devices to be operated in the
automation system and the required timing, a DP/PA coupler or, in the
case of higher requirements, a more powerful DP/PA link is used.
Field
PROFIBUS-PA
FD
FD
Introduction
T
additional
cable
termination
19
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