Siemens S5-135U/155U System Manual page 71

The modular packaging technique allows variable configuration of a CC with
modules and its adaptation to the particular automation task.
The various modules carry out the following tasks:
System Manual
C79000-G8576-C199-06
Central Controllers and Expansion Units Power Supply Units
CPU
The CPU processes the input signals of the PLC according to the user
program, and emits the results as output signals. The following CPUs can
be used in the S5-135U/155U PLC
– CPU 948
– CPU 928B
– CPU 928
– CPU 922
Coordinators
By using a coordinator, you can configure the S5-135U/155U as a
multiprocessor controller with up to four task-oriented CPUs in different
combinations. Each CPU processes its program independently of the
others.
I/O modules
The I/O modules provide the link to the process.
IP module
The intelligent I/O modules (signal pre-processing modules) off-load the
CPU by independently executing compute-intensive tasks such as
controlling, counting and positioning.
Interface modules (IMs)
If your CC has insufficient slots to insert all the modules required for your
automation task, you can increase the number of modules with expansion
units. The IM modules provide the link between central controller and
expansion units.
CP module
CP modules allow point-to-point communication for data interchange
between two PLCs, between one PLC and an external unit, between one
PLC and a SINEC bus system or between one PLC and the COROS
operator control and process monitoring system. You can use additional
CP modules, such as the CP 581, CP 516, for the acquisition, storage,
administration and preprocessing of large volumes of data.
VP module
VP modules enable the local acquisition and displaying (visualization) of
process data of a PLC of the SIMATIC S5.
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