Central Controllers And Expansion Units, Power Supply Units - Siemens S5-155U System Manual

Central Controllers and Expansion
Units, Power Supply Units
System Manual
C79000-B8576-C199-03
The S5-135U/155U programmable controller comprises a central
controller (CC) and, depending on the configuration, one or more
expansion units (EUs). Expansion units are connected when there are
unsufficient central controller slots, or when you wish to position I/O
modules as closely to the process as possible (see also Chapter 2).
With the central controllers and some expansion units, the modules
are directly powered and cooled via the integrated power supply
plug-in module. With all other expansion units, power is supplied via
the IMs from the CC (see also Chapter 7).
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