GE VersaPoint IC220PB001, User Manual

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5-2 VersaPoint™ I/O System Profibus-DP NIU User’s Manual – August 2005 GFK-1911B
5
Supply of the Profibus-DP Network Interface Unit
Logic and field power are distributed among VersaPoint I/O modules on several
dedicated power circuits.
These are:
The main power circuit (U
M
), which powers all modules that do not need to be
separately switchable from the main circuit. The main power circuit begins at
the power terminal integrated into the NIU. It may also include additional
Power Terminal modules as appropriate.
The segment voltage (U
S
) is drawn from the main power circuit at the NIU, at
a Power Terminal module, or at a Segment Terminal module. A 24V segment
circuit can be used to power I/O modules that must be separately switchable
from the main voltage. One or more segment circuits might be created for
discrete input modules without individual short-circuit protection, for discrete
output modules, and to control power switches and contactors.
Logic Voltage (U
L
) is generated from the main power circuit at the NIU and
provides communications power for all I/O modules in the station. This voltage
is not augmented by the addition of extra power terminals.
Analog Voltage (U
ANA
) is supplied by the NIU and used to power the analog
modules in the I/O Station. This voltage is not augmented by the addition of
extra power terminals.
Each of these power circuits is described in this section.
The
main power U
M
and the segment voltage U
S
for the station are connected at the
Network Interface Unit. The main power generates internal voltages for the logic
circuit U
L
and analog signals U
ANA
. The segment voltage supplies the sensors and
actuators.
NIU
Power Terminal Segment Terminal