Connecting the PSSu system
Installation Manual PSSuniversal
21262-EN-07
40
6
Connecting the PSSu system
6.1
Supply voltages
All PSSu system voltages are supplied via the head module or via supply voltage modules.
If the supply voltage is not integrated within the head module, a separate supply voltage
module will be required. The voltages are distributed to the modules via the module bus.
}
Module supply
The module supply is the internal supply voltage for the head module, the compact
modules and the electronic modules.
}
Periphery supply
The periphery supply supplies 24 VDC to the sensors and actuators on digital input/out-
puts on electronic modules. On compact modules, the supply for the inputs is gener-
ated from the periphery supply; the supply for the outputs must be fed to the module
terminals.
The connection on the module bus can be disconnected in order to form supply groups.
On digital failsafe modules, the periphery supply is used to provide test pulses. Failsafe
input/output modules will not start until the periphery supply is connected correctly. On
analogue input/output modules, the periphery supply is galvanically isolated from the in-
puts/outputs.
}
C-rail
The C-rail is an additional, free power rail. Access to the C-rail is available via base
modules that contain the letter “
-C
” in their description (e.g. PSSu BP
-C
1/8 S, PSSu
BP
-C
1/8 C).
The C-rail supply must belong to the same circuit as the other base module connec-
tions. Connecting PE to the C-rail provides a simple form of shield. On the compact
modules, the C-rail is not looped through and is not available at the terminals. Permitted
infeed at the C-rail:
– PE
– 0 V
– Screen
– - 30 VDC ... + 30 VDC
– - 48 VAC ... + 48 VAC
}
Inputs/outputs on the analogue modules and counter modules
The inputs and outputs on the analogue modules and counter modules are galvanically
isolated from the periphery supply. On the base modules, the supply for the outputs is
generated from the periphery supply.
}
Earth (Ground)
The module supply and periphery supply have separate connections for the respective
earth potential (Ground).
}
Functional earth
A contact spring on the base modules and compact modules connects the modules'
functional earth to the mounting rail.
