Moniteur 50 Series SMART Positioners - Manual (Page 15)

Introduction
1-5
Positioner SIPART PS2/SIPART PS2 PA
C79000-G7476-C150–01
In addition to the EN standard 50170, the PNO (PROFIBUS user orga-
nization) has defined the functionality of the individual field device types
in a profile description. These profiles define minimum functional re-
quirements and optional extensions. The device–internal ”device man-
agement” provides the configuration tool of the control system with all
basic information necessary to locate the profile parameters. In that
way, one parameterizing tool can operate all profile–compliant devices,
whatever their type or manufacturer.
The system must be implemented with one or more PROFIBUS PA
trains depending on the automation task and therefore the number of
field units and the required time response. One PROFIBUS PA train
consists of the components shown in Fig. 1-2.
PLS, PC
Coupler
Power
supply
FG FG
T
additional
line termination
PROFIBUS PA
PROFIBUS DP
Control room Field
T
Fig. 1-2 PROFIBUS PA architecture
Control is performed by the central process control system PCS or for
low requirements, by a PC. Usually, the functional signal conversion
DP–PA, bus feed, and bus termination are combined into one linking
module. Depending on the number PROFIBUS PA field devices to be
operated in the automation system and the required time response, a
DP/PA coupler or for higher requirements, a more powerful DP/PA link
is used.
For transmission reasons, the bus must also be fitted with a terminating
resistor T at the remote end. If the recommended bus cable is used,
the theoretically possible maximum line length (sum of all line sections)
is 1900 m.
During configuration, the power requirement of the individual stations
and the voltage drop on the cable must also be taken into account. The
individual FG field devices can be connected to almost any point in the
bus system. For further information see the ”PNO–Leitfaden PROFI-
BUS PA”/1/.
DP/PA couplers or DP/PA links are powered from a power supply unit
with SELV (safety extra–low voltage). This power supply unit must
have sufficient back–up reserves to provide back–up power during
short power interruptions.
Profiles
Link