Siemens Simatic PCS 7 Function Manual page 36

High availability solutions in PCS 7
4.1 Solutions for the I/O
Network components that are integrated at the fieldbus belong to the distributed I/O. These
include, for example, the following network components:
● Bus links
– DP/PA-Link
– Y-Link
– FF-Link / Compact FF Link
● PROFINET switches
With the PROFINET switches, you integrate PROFINET networks in the fieldbus of an AS.
● Compact Field Unit
The Compact Field Unit, as a PROFINET IO device, combines the effort of distributed I/O
for digital IO and bus link for field devices on PROFIBUS PA.
An AS interface can be connected using AS-Interface master modules (CPs) that are used in
the distributed I/O device. This enables the connection of simple sensors and actuators to
PCS 7 with AS-Interface. PCS 7 integrates other I/O levels in a project in this way.
Increasing availability
The availability of the I/O can be increased through the following configuration options:
● Redundant I/O (distributed I/O)
The entire signal path up to the sensor/actuator is configured redundantly. Additional
information on this topic is available in section "Redundant I/O (Page 38)".
● Switched I/O (distributed I/O)
The communication path to the I/O (station) is redundant. There is only one input/output
module (SM) for processing a process signal.
Additional information on this topic is available in section "Switched I/O (Page 42)".
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The DP/PA‑Link enables the connection of a lower-level bus system such as PROFIBUS
PA to a redundant PROFIBUS DP.
With the Y-Link, you connect singular PROFIBUS components to a redundant system.
This bus link enables the connection of a lower-level bus system such as FOUNDATION
Fieldbus to a redundant PROFIBUS DP.
High Availability Process Control Systems (V9.0)
Function Manual, 05/2017, A5E39221836-AA