Siemens SIMATIC S7-400H - Redundant Cpus with a Single-Channel, One-Way or Switched I;O; System Configurations with Distributed I;O

Characteristic Values of Redundant Programmable Logic Controllers
A-6
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
A.2.2 System Configurations With Distributed I/O
The following system with two fault-tolerant CPUs 417-4 H and a one-way I/O is
taken as a basis for calculating a reference factor which specifies the multiple of
the availability of the other systems with a distributed I/O compared with the
baseline.
Redundant CPUs with a single-channel, one-way or switched I/O
One-way, distributed I/O Baseline
PS 407, 10 A CPU 417-4H CPU 417-4H PS 407, 10 A
IM 153-1
SM 321
SM 322
ET 200M
2 fiber-optic cables
1
Switched distributed I/O Factor
PS 407, 10 A CPU 417-4H CPU 417-4H PS 407, 10 A
IM 153-2
SM 321
SM 322
DP
DP
ET 200M
2 fiber-optic cables
IM 153-2
3 or. 12 *
* A factor of 3 applies to the condition when the failure of an I/O module has resulted in the entire system
stopping. A factor of 12 applies when the failure of an I/O module has not resulted in the entire system
stopping.