Switched I/O - Siemens SIMATIC PCS 7 Function Manual

Fault-tolerant Solutions in PCS 7
3.1 Solutions for the I/O
Installation rules
The configuration always has to be symmetrical when using redundant I/O. Follow these
installation rules:
● Both subsystems of the S7 400H must be configured identically. The same modules are
● The communication paths and interfaces must be configured the same way in both
● Redundant modules are always the same (order number, firmware version)
Configuration rules
● A DP slave must have the same PROFIBUS address in the mutually redundant DP master
Additional information
● Section "Redundant interface modules in distributed I/O (Page 32)"
● Section "Redundant I/O modules (Page 33)"
● Manual
3.1.2

Switched I/O

Switched I/O
Switched I/O describes the situation when there is only one I/O module (SM) for processing a
process signal. The communication path to the I/O (station) is redundant. In the event that a
communication path fails, the distributed I/O (station) switches to the functioning
communication path. The non-redundant I/O modules of the distributed I/O can be addressed
via the redundant interface module (DP slave) of both central modules (CPU) of a fault-tolerant
system.
30
located at the same slots.
Example: CPU and CPs are located in both subsystems at the same slot.
subsystems.
Example: The PROFIBUS cables in both subsystems are connected to the same
PROFIBUS DP interface of the CPU 41x-4H.
systems.
Automation System S7-400H; Fault-tolerant Systems
Fault-tolerant Process Control Systems (V8.0)
Function Manual, 03/2012, A5E02779471-02