Components In The Distributed I/O; Redundant Interface Modules In Distributed I/O - Siemens SIMATIC PCS 7 Function Manual

Fault-tolerant Solutions in PCS 7
3.1 Solutions for the I/O
The system remains available even when one component in part of a line of the redundancy
node fails. There is only one I/O module and therefore no corresponding redundancy node. It
is the weakest link in the complete system's chain.
Installation rules
The configuration always has to be symmetrical when using switched I/O. Follow these
installation rules:
● CPU 41x-xH and additional DP masters must be located in the same slots in each
subsystem (for example, in slot 4 of both subsystems).
● The PROFIBUS cables in both subsystems must be connected to the same interface (for
example, to the PROFIBUS DP interfaces of the two CPU 41x-xH).
Configuration rules
● A DP slave must have the same PROFIBUS address in the mutually redundant DP master
systems.
Additional information
● Section "Redundant interface modules (Page 36)"
● Manual
3.1.3

Components in the distributed I/O

3.1.3.1

Redundant interface modules in distributed I/O

Redundant interface modules
By using two interface modules in one distributed I/O device, the following can be implemented:
● Setup of a switched distributed I/O
● Setup of a redundant distributed I/O
If the active interface module or the communication path fails via this interface module, the
passive interface module takes over the relevant functions without interruption. The active
interface is indicated by an illuminated "ACT" LED on the respective interface module.
Configuration:
36
Automation System S7-400H; Fault-tolerant Systems
Fault-tolerant Process Control Systems (V8.1)
Function Manual, 11/2014, A5E34878832-AA